Abstract: Based on the population of root knot nematode in soil, degree of root knot and growth and yield of cucumber, this paper studied on control effect of soil solarization by black plastic film mulching on root knot nematode (Meloidogyne incognita) of cucumber. Results showed that the population of root knot nematode in solarized soil at 5 cm, 10 cm, 15 cm, 20 cm, 30 cm decreased by 26.9%, 13.9%, 2.9%, 1.9% and 0.9% compared with the check, unsolarized and disinfested by chemical nematicides, even after a growing season. The controlling effect decreased with the soil depth. Also, the number of phytoparasitic nematodes decreased by 5%. The nematodes, declining in number with soil depth, mainly distributed in 0～30 cm and accounted for 97.7%～98.5% of the total. The damage to root growth of the solarized(the Ⅰ degree) group was significantly lower than that of the check(the Ⅳ degree). The soil solarization increased not only the cucumber yield, but also quality. Meanwhile, the cost of the solarization with plastic film mulch was 57% less than that of the check, and it is environmentally friendly. Though the unsatisfactory effect revealed by the number of the nematodes, the controlling effect of solarization was better than that of the check in growth, yield and content of root knot nematode. This suggested that the control of root knot nematodes by solarization with black plastic film mulch was characterized by the decreased vigor, infectibility and the delayed infection. It is preliminarily concluded that soil solarization for 40 d under the wet weather can effectively control the incidence and damage of root knot nematode.