Abstract: Abstract: We all know that some functional microorganisms can dissolve insoluble phosphates and it is different from the abilities of the same strain mobilizes different phosphates. The experiments of plate cultivation and shaking culture were carried out to explore the abilities and mechanisms of Penicillium oxalicum HB1 to mobilize different insoluble phosphates (Ca3(PO4)2, phosphate rock powder, FePO4, AlPO4) when different forms of nitrogen (NH4+-N, NO3--N) were supplied in the growth medium. Furthermore, a soil incubation experiment was conducted to verify the capacity of HB1 solubilizing insoluble phosphate in two types of soils with low and high levels of available phosphorus. The results of plate cultivation showed that phosphate dissolving zone was observed on each plate with different phosphates of Ca3(PO4)2, phosphate rock powder, FePO4 and AlPO4. The calculated ratios of phosphate solubilizing zone and bacterial colony followed the trends of Ca3(PO4)2 > phosphate rock powder > FePO4 > AlPO4, which indicated that the ability of HB1 to dissolve Ca3(PO4)2 was better than others. In order to prove the abilities of HB1 mobilizing different insoluble phosphates further, the shaking cultural experiment was set up and the results clarified that the phosphate solubilizing capacity of HB1 varied with different mineral phosphates and two different forms of nitrogen in growth mediums. When Ca3(PO4)2 or FePO4 was supplied, the concentrations of phosphorus (P) in the nutrient solution with HB1 were 884 mg/L or 265 mg/L on the condition of NH4+-N, and 945 mg/L or 206 mg/L with NO3--N addition, respectively. However, there was no significant difference in P concentrations of solution between NH4+-N or NO3--N addition. Meanwhile, HB1 enhanced phosphorus released from Ca3(PO4)2 markedly compared with FePO4, which illustrated that P concentrations in solution with HB1 and Ca3(PO4)2 were 2.34-3.59 folds higher than those of FePO4 in the growth medium. Moreover, when phosphate rock powder and NH4+-N supplied, the concentration of phosphorus in the solution with HB1 was 199 mg/L, which was 7.14 times of that of NO3--N situation. However, the concentration of phosphorus in the nutrient solution with HB1 was 120 mg/L when AlPO4 and NO3--N applied, which was 3.29 times of that of NH4+-N. Therefore, shaking cultural experiment demonstrated that Penicillium oxalicum HB1 dissolved the P from different insoluble phosphates indeed and the rank of P mobilizing ability followed Ca3(PO4)2 > phosphate rock powder and FePO4 > AlPO4 when NH4+-N supplied in growth medium, whereas followed Ca3(PO4)2 > FePO4 > AlPO4 > phosphate rock powder when NO3--N applied. It suggested that different N forms in growth medium did not affect the ability of HB1 dissolving P from Ca3(PO4)2 and FePO4, but influence this ability for AlPO4 and phosphate rock powder. NH4+-N is better for HB1 to mobilize phosphate rock powder, and NO3--N applied is a benefit for HB1 to dissolve AlPO4. Furthermore, there were significant negative relationships between P levels and pH in growth medium with NH4+-N, which indicated the possible mechanisms that Penicillium oxalicum HB1 could exudate H+ to the solution, then decreased pH in the growth medium, and finally enhanced the releases of P from different insoluble phosphates. The ability of HB1 dissolving insoluble P was proved in the experiment of soil incubation as well. The results showed that concentrations of available phosphorus in HB1 treatments increased by 45.00% and 14.17% in low-phosphorus soil and high-phosphorus soil after incubation for 21 days, respectively. In summary, HB1 had the strongest phosphate-dissolving capacity for Ca3(PO4)2, followed by FePO4 and phosphate rock powder when NH4+-N addition, which was dissolved through H+ exudate by Penicillium oxalicum HB1. It would be a better pathway to use HB1 mobilizing insoluble phosphate in soils with low available phosphorus.