Solenocera crassicornis, also known as red shrimp, is one of the main marine aquatic products of China. It is much-loved by consumers and producers for its good flavor and rich nutrition. Currently, many types of shrimp are sold in the market, such as fresh shrimp, frozen shrimp, dry shrimp or shrimp surimi products, etc. Surimi is a kind of thermally gelated food that was widely accepted by the public because it is rich in protein and low in fat, and is valued for its unique gelling properties. However, due to the physiological and biochemical characteristics of red shrimp meat, it is difficult to form competitive advantage because of poor gel forming and unstable quality, which greatly restricts the development of shrimp surimi products. It is very important to improve the gel properties of shrimp surimi. Compared to the native starch, modified starch usually has better gelatinization performance and be used as additives to significantly improve the performance of the gel. Hydroxypropyl distarch phosphate (HPDSP) is a modified starch which has attracted much attention for its good filling effect, stable gelation properties and low cost in food industry. In order to investigate the effect of HPDSP on improving the gel properties of S. crassicornis shrimi gel, 1%, 3%, 5%, 7% and 9% addition of HPDSP were respectively added to the shrimp surimi. Using the gel strength, texture profile analysis, water holding capacity (WHC), gel microstructure as the indicators, and combined with the analysis of the secondary structure of myofibril protein from shrimp surimi sol, gelatinized shrimp surimi and surimi gel by circular dichroism spectrum, the effects of HPDSP on the gel performance of shrimp surimi and its mechanism were explored. The results showed that HPDSP can increase the gel strength and WHC of shrimp surimi gel, and reached the maximum value when the addition amount was 7%. Furthermore, HPDSP reduced the a* value and b* value of the shrimp surimi gel, but the L* value and whiteness did not change significantly except for the 9% additive group. An appropriate amount of HPDSP could improve the hardness, springiness, cohesiveness and chewiness, and promote the formation of a denser and stabler gel network structure of the shrimp surimi, which was consistent with the gel strength and WHC. In addition, during the gelatinization of shrimp surimi, heating increased the contents of β-sheet and random coil, but decreased the content of α-helix in myofibrillar protein. At the same time, HPDSP affected the thermal denaturation and aggregation of myofibril protein, thereby changing its secondary structure and affecting the formation of shrimp surimi gel. Overall, adding 7% of HPDSP could significantly enhance the gel properties of shrimp surimil. The results of this study would contribute to the utilization of HPDSP for the functionality of surimi products improvement.