The wide/narrow viewing angle switchable thin film transistor liquid crystal display has the problem of moire pattern, which is caused by the continuous change of the phase between the pulse width modulation signal of backlight and the driving signal applied to the display panel under the narrow viewing angle mode. This paper presents a feasible solution. Since root cause of the moire pattern is identified as the signal interference, our solution is to synchronize the signals so as to minimize the phase difference. The experimental results show that, by synchronizing the display panel’s start vertically signal and backlight module’ pulse width modulation signal, the moire pattern could be significantly suppressed. Under a pulse width modulation signal with 1 kHz, 49.8% duty cycle, the value of the flicker in the center area of the moire is from 68.5% to 72.3% under 64 gray scale measured by using the display color analyzer CA-310, and then becomes stable at 69.9%. Based on this scheme, the actual observation of moire is not noticeable, thus it can give users good viewing experience under narrow viewing angle mode.