Abstract: Impulse coupling-coefficient is an important index, which represents the capability of laser energy transforming kinetic energy. Based on the measure displacement method of high-speed photograph technology, using Kalman filtering method, velocity calculated method of lightcraft is proposed for horizontal parallel wire supported laser propulsion. From the proposed testing and calculation method, the problem of velocity random fluctuating phenomenon owing to test data fluctuating is resolved. The presented method can be used in engineering measure and design for calculating impulse coupling-coefficient of laser propulsion.