The utility model discloses a high speed automatic chain assembly line and consists of an assembly lathe bed and a bin arranged on the assembly machine. A motor is arranged on the lathe bed; the motor drives the main shaft through a belt pulley and gears; a master cam, two inner bore locating cam and a bevel gear are arranged on the main shaft. Each of the inner bore locating cam is provided with a roller wheel connecting rod which locates the inner bores of external and internal chain pieces respectively. The bevel gear transfers to two straight tooth shafts, which are connected with two cams respectively. The master cam and the roller wheel are connected with a pressure axle bed through a connecting rod; a nail and a pressed block are arranged on the pressure axle bed, and a mould part is arranged under the pressure axle bed. On the mould part, the cam on a straight tooth axle drives the connecting rod to push a slipper to move. Another two cams driven by the bevel gears are additionally arranged on the mould part; the cam drives the connecting rod to push the slipper to move. The main machine is connected with a pretension break-in part through a storage disc; the pretension break-in part is connected with a dismantling snaphead through the storage disc. The utility model is suitable for large-scale assembly of chains.