The Linchang Composite Granite Batholith (LCGB) of west Yunnan is an important constituent of the collision-related granite belt of a Permian-Triassic suture zone in this area. It consists of Pinhejie granite in the north and Linchang granite (LG) in the south, which are connected with each other at depth. The Pinhejie granite is N.N.W.-trending, 70 km long, 3-9 km wide and 450 km2 in area. Its eastern part is Pinhejie gneissic granite (PGG), with an Rb-Sr isotopic age of 309 ± 27 Ma and an initial Sr ratio of 0.7153 ± 3. Its western part is Pinhejie massive granite (PMG), with an Rb-Sr isotopic age of 294 ± 6 Ma and an initial Sr ratio of 0.7205 ± 3. The LG is an extremely large batholith, with a total length of 370 km, a width of 18-36 km and a total area of some 10000 km2. The Rb-Sr age of Rb-Sr isochron line for LG and PMG could be obtained with an age of 292 ± 15 Ma and an initial Sr ratio of 0.7216 ± 7. These data show that emplacement of LCGB took place approximately in the range of 292-275 Ma, i.e. in the Permian period. The modelling composition of source materials for LG is equivalent to a mixture consisting of 80% upper crustal Sr plus 20% lower crustal Sr. It suggests that the collision-related LCGB is a typical peraluminous S type granite in genesis.