In order to guide the structure design of the single-fin Terminal Sensitive Ammunition (TSA), the installation and connection mode between the projectile and the single-fin was analyzed. Three fin-setting-angles were defined, meanwhile their mechanical description method was given. Using the dynamic model of quaternion method, based on the structural and pneumatic parameters of a certain type TSA, the numerical integral calculation was performed during which only the fin-setting-angle changed. The relationship between scanning angle, scanning frequency, falling speed, scanning interval and the 3 fin-setting-angles was achieved. The results show that the three finsetting-angles have a great influence on the scanning angle, scanning frequency, falling speed and scanning interval when other parameters are unchanged.