Abstract:To satisfy of chain saw the trend needs to increase the speed of the saw chain pitch also tends to reducing. The chain sprocket design theory is applicable for more than 15mm(t≥15mm) chain pitch of chain saw and chain sprocket design in the domestic and overseas, but for less than 10 26mm(t≤10.26mm) chain pitch chain sprocket design the application of current chain sprocket design has some faults and limitation. This paper set up an improved theory for design and calculation in the saw chain sprocket. Using this chain sprocket design theory the utilization of energy can be improved vibration reduced, and the piece using time enlonged.