Aimed at the problem of dynamic false contour in LED display when playing the motion images, a novel of PWM method named concentrated gated pulse width modulation was proposed. Based on the GPWM, the approach fixes the decimal subfields on the center of one PWM period, and then figures out the number of subfields corresponding to the integer weight bits, and locate them near the decimal subfields. Theoretical analysis and experiments show that CGPWM has the similar lighting function with linear PWM, and consequently reduces the average DFC values between any two gray levels from 0.6 under the control of GPWM to 0.2. CGPWM can eliminate DFC effectively while maintaining high refresh frequency and rich gray levels, and thus improve the image quality greatly. Furthermore, the processing to implement CGPWM is simple without extra hardware.