According to the semi-active laser guidance weapon’s technology status that its pulse repeating frequency coding is easily interfered, a new idea of laser pulse width coding is proposed to improve its anti-interfering capability. The technology p rincipal of laser pulse width coding is analyzed, and the feasibility of engineering realization has been demonstrated preliminarily. A kind of pulse width tuning laser realization project applying electro-optic chopping wave technology is proposed. The academic design of this pulse coding laser has been finished. The primary analysis approved the feasibility of the project.