Abstract: Abstract: An important factor in Litopenaeus vannamei culturing process is water quality, whose stability for shrimp pond has close relationship to the community structure of microplankton. How to control water color is the key to Litopenaeus vannamei breeding, especially to the controlling of the species and amount of microplankton, The dominant species accounted for 49%~99% of the total in most cases, and the amount of microplankton depends on the amount of dominant species. To explore a new biological control system, environment control technology based on the jet flotation machine in Litopenaeus vannamei culturing process was studied in this paper. Two Litopenaeus vannamei culturing ponds with the same 667 m2, in which we put the same number of shrimp seed at the same time, were used, one for biological control test, the other for contrast. The new biological control system, in which we added a loopback for the water treatment, was composed of a 7.5-kilowatt motor, a 7.5-kilowatt water pump and a 1.5-kilowatt jet flotation machine. The jet flotation machine, which ran 24 hours a day during experiment, was placed in a glass fiber reinforced plastically (size: 2 m×1.5 m×1 m). The level of ammonia nitrogen and nitrate nitrogen was tested by sodium hypobromous acid oxidation and diazo-azo at 9:00 am, while the species and amount of microplankton were recorded by a nikon AZ100 microscope at 14:00 pm. The dissolved oxygen, temperature, potential of hydrogen and salinity of two ponds were measured by YSI ProODO and YSI Proplus three times a day regularly. Number of vibrio was recorded every day. The length and weight of shrimps were measured by electronic balance and vernier caliper every 20 days. Experimental group and control group were labelled as A and B groups, respectively. Research results showed that there was no significant difference in the potential of hydrogen between A and B groups based on the same amount of feeding, and the potentials of hydrogen of the two groups did not exceed the expected range of Litopenaeus vannamei. Besides, the level of ammonia nitrogen of A group was lower than that of B group significantly. The same is true for the level nitrate nitrogen. For the first and second weeks the species of microplankton in A group and B group were both diatoms and green algae. This was not changed in A group for the third, fourth and fifth weeks, but a large number of green algae and a small amount of cyanobacteria were found in A group for the sixth week. The species of microplankton in B group was a large number of green algae and a small amount of cyanobacteria in the third week and green algae and cyanobacteria in the other time. Level of total bacteria of A group was significantly lower than that of B group except for the fifth week. The level of fluorescent bacteria of A group was significantly lower than that of B group except for the third week. There was no significant difference in the length and weight of shrimp between A and B groups in twenty days. In forty days, however, the shrimps of A group were significantly longer and heavier than those of B group. In conclusion the new biological control system has certain effect in Litopenaeus vannamei culturing process.