Abstract: As the development of jacquard technology of tufted carpets, the phenomenon of higher transitional loop which seriously influence the effectiveness of multi-level loop jacquard in all kinds of jacquard systems has to be eliminated. The dynamic characteristic response time of step motor is the fundamental cause leading to the phenomenon in the system of step servo jacquard, which is explained through mathematical model of velocity control. For solving this problem, the analytical equation of speed curve was derived from the dynamic characteristics equation of step motor. The amount of compensation was accurately calculated based on the equation. The compensation program based on index shaped curve was selected through comparing S-shaped curve with index shaped curve. Furthermore, a set of single-chip control program was proposed to solve the problem. The compensation program can improve the flexibility of the step servo in control the jacquard system.