In the territory of SW China and SE Asia, between 100-120º east longitude, there is a NS trending syncollision tybe granite belt, At the northern end this granite belt begins with Lincang granite body (LG) and Pinghejie granite body (PG), W Yunnan, It runs southwards to join the medial granite zone of Thailand and the western granite zone of Malaysia, These two granite bodies with total exposure of 11000 km2 have typical features of continental crust-derived origin. The main characteristics are; (1)Peraluminous, with ANKC values greater than 1, 00 (1, 082 for PG and 1.106 for LG)，(2) Rich in potash relative to sodium, with Na/K ratios less than 1.00 (0. 88 for PG and 0. 95 for LG);( 3 ) Relatively lower in Sm/Nd ratios (0.17 for PG and 0. 20 for LG);( 4 ) Relatively higher in Rb/Sr ratios (1. 35 for PG and 2. 03 for LG)，( 5 ) Enriched in Sn (13. 7 ppm for PG and 14. 6 ppm fer LG)，(6) Higher in initial Sr ratios (0. 7205 for PG and 0.7340 for LG);(7) Negative:εtNd values(-12. 6 for LG) etc, The source materials for these two granite bodies are considered to be a mixture of about 70-80% upper continental crust and 20-30% lower continental crust materials by modelling using mixing two different Sr and Nd isotope isotope compositions proposed by Faure (1986).The magma for LG and PG was generated from 30-35% partial melting of this source material based on the partial melting equation of Rb, Sr, Rb/Sr proposed by Shaw.