Shack-Hartmann wave-front sensor has been widely used in laser-beam quality measurement, for its acquisition of intensity and phase of laser beam simultaneously. It is an important procedure in the construction of the measurement system to design the system parameters of the Shack-Hartmann wave-front sensor according to the requirements in actual laser beam test. The parameters of the Shack-Hartmann wave-front sensor are designed with considerations of the requirements of the precision, sensitivity and dynamic range, as well as the mutual restraints among them. The design procedure is given and the laser-beam measurement system is constructed successfully with the designed parameters. The actual Shack-Hartmann wave-front sensor in single aperture with dynamic range of 3.7λ (λ=632.8 nm), sensitivity of 0.01λ, and Fresnel number of 2.468, satisfies the requirements of the laser-beam measurements in practice.