HPAM gel is the most widely used and most effective chemical water shutoff agent at home and abroad. Phenol/formaldehyde is commonly used for crosslinking agent of HPAM gel. However, its high toxicity，especially the carcinogenic，restricts its application severely in the oilfield. In this paper，a lowtoxicity crosslinking agent was synthesized firstly，and then the geation kinetic of HPAM crosslinking with the composite crosslinker was studied，in which THMBPA was the main crosslinking agent and polyethylene polyamine TET as assisting crosslinking agent. The influence of temperature，initial pH，composite crosslinker ratio and salt concentration on the gealtion time and long term stability were investgated. Experimental results showed that the gelation time of the gel system can be arbitrarily adjusted at the range of 10~120 h at 120 ℃，and gel could remain stable for 90 days at 120 ℃ and 100 days at 120 ℃. Long sand packed tube plugging experiments showed that the water shutoff agent had good sealing ability and plugging rate could reach 90.6%.