In order to improve the poor strength and deterioration of the unrinsed surimi gel， the effects of three different ionic polysaccharides， including carragenan， konjac gum and chitosan， on the physical properties， low-field NMR， rheology and microscopic imaging of the unrinsed surimi gel of tilapia were analyzed. The results showed that， compared with the blank (47.81)， the maximum whiteness values of different polysaccharides (carrageenan， chitosan， konjac gum) were 93.07， 80.88 and 73.95， indicating that the improvement effect of carrageenan was the best， and the whiteness values of the three polysaccharides were the maximum when the addition amount of all three polysaccharides was 1%. The results of water retention showed that: compared with the blank (88.18%)， the water retention of 1% carrageenan was the highest (92.51%). The T22 relaxation peak area in low-field NMR indicated that the content of unmobile water in carrageenan was higher， indicating that the gel network was more compact and ordered. In terms of texture， carrageenan supplementation significantly increased the hardness of surimi compared with the blank group without polysaccharide (P＜0.05)， the hardness increased by 155.44， 1 168.21 g and 2 252.2 g at 0.5%， 1% and 2%， respectively. The masticability was increased by 93.53， 700.99 and 1 108.22， respectively， and the results showed that the content of polysaccharide ≥1% could significantly improve the texture characteristics of surimi. In terms of gel strength， the gel strength of carrageenan showed great improvement， and compared with the gel strength of the blank group sample (1 585.54 g·mm)， the gel strength of 2% surimi gel reached 3 765.35 g·mm. Rheological properties showed that all three polysaccharides could increase the energy storage modulus (G') of surimi gel at constant temperature. The protein secondary structure showed that the conformation of surimi protein was changed by adding carrageenan and chitosan. Microscopic observation of eosin staining showed that with the increase of polysaccharide content， the region of polysaccharide phase became larger and larger， and the microstructure of surimi gel in the protein phase region of carrageenan added among the three polysaccharides was dense. The electrophoretic map showed that the addition of carrageenan did not change the color of the bands， and it was speculated that polysaccharide played a main role in filling the surimi gel. In conclusion， the addition of carrageenan is more beneficial to promote the formation of gel network and improve the gel quality of tilapia surimi.