The invention provides a sweep frequency laser light source based on a liquid crystal tuning filtering device, including a semiconductor light amplifier, a tuning filtering device, an optical fiber coupler, and a light enhancement output device. The tuning filtering device comprises a multi-level Lyot filter module and a multi-channel signal generator for driving the multi-level Lyot filter module. The optical fiber coupler is used for dividing the sweep frequency laser into an output sweep frequency laser and a return sweep frequency laser. The multi-level Lyot filter module is an m-level Lyot filter module consisting of m + 1 polaroids and m liquid crystal cells alternately arranged in turn. The multi-channel signal generator has a driving signal generating module, a signal transmission module, a digital-analog conversion module and m electrical signal output ports. The m electrical signal output ports and the m liquid crystal cells are in one-to-one correspondence, and electrical signals are simultaneously loaded to the m liquid crystal cells. The sweep frequency laser light source is based on the liquid crystal technology to achieve tuning filtering, and can provide the sweep frequency laser with the small passband bandwidth.