Abstract: In order to understand the effects of different transformation methods on the diversity of understory vegetation of Pinus.massoniana forest,the untransformed P.massoniana forest in Hetian Town,Changting County was used as the CK,interplanting after clear cutting (density is 2500 plants·hm^-2) of five bandwidths(6,8,10,15,20 m) and six kinds of different interplanting densities(900,1050,1200,1350,1500,1650 plants·hm^-2) after selective cutting (reserved density 1200 plants·hm^-2) of P.massoniana transformation(in 2020) forest were studied,the vegetation diversity and light intensity of understory vegetation were investigated in October 2022.The results showed that the light intensity in the forest,the number and diversity of understory vegetation increased of P.massoniana forest after transformation by two measures.The understory vegetation species(19 species) and species richness index (0.1557),Simpson diversity index (0.9405),Shannon-Wiener diversity index (2.7836),Jsi (0.9928) and Jsw (0.9952) of P.massoniana transformation forest after clear cutting and interplanting with a bandwidth of 8 m were the best.The understory vegetation species (11 species),richness index (0.1597),Simpson diversity index (0.8984),Shannon-Wiener diversity index (2.3356),Jsi (0.9882) and Jsw (0.9840) of P.massoniana transformation forest with the density of 1200 plants·hm^-2 were the best.It shows that the reasonable bandwidth of strip clear cutting transformation of P.massoniana forest in the region is 8 m,and the best interplanting density of selective cutting and interplanting transformation is 1200 plants·hm^-2.