With the rapid development of network technology，online fitting is becoming a new consumption of clothing for people．Online fitting is almost based on 2D until now，and is lack of all-round display．There are some 3D fitting systems based on modeling and rending，but they are too complex to produce，high cost and poor color reproduction，so they are not effective．Therefore，this paper puts forward 3D online Fitting System based on Flash．It uses photographs for 3D display of clothes．This system has a high practical value．