Abstract: The effect of 4 food- grade protease inhibitors ethylenediaminetetraacetic acid( EDTA), sodium pyrophosphate(PPi),bovine plasma(BP) and potato power(PP) on the gel hardness,springiness and water loss rate of Ryukyu squid surimi in South China Sea was studied. The SDS-PAGE was used to analyze the relevant mechanisms. The results showed that the PPi,BP,PP could enhance the gel properties of Ryukyu squid surimi,maximum hardness and springiness were obtained by adding 2% TGase,250 mg/kg EDTA,0.3%PPi,3% BP and 3% PP. SDS-PAGE indicated that the 4 food-grade protease inhibitors combine with TGase could promote the gel formation of Ryukyu squid surimi. TGase couldn't form covalent cross-linking with Actin.The PM was involved in the the gel formation of Ryukyu squid surimi in South China Sea was studied.