Four mating types of basidispores in 3 strains of Pleurotus ostreatus were determined using a nuclear migration test and an OWE-SOJ technique. The nuclear migration test showed that nuclear migration only occurred in A=B≠ mating interaction but did not in A≠B= interaction. In OWE-SOJ test, a fluffy colony without clamp connection formed in the A=B≠ mating interaction where nuclear migration occurs, while a barrage colony without clamp connection formed in A≠B= interaction where nuclear migration do not occur. The two colonies could be distinguished clearly each other. The result of the nuclear migration test is consistent with that of OWE-SOJ, which could be corroborated each other. Therefore it is feasible to apply the two to accurate determination of mating types in Pleurotus ostreatus.