Based on the multi-beam interference principle, the Gaussian beam transmitted-intensity expression on a non-parallel angle-tuned thin-film filter in oblique incidence has been derived. According to the result, the influence of the transmitted-intensity distribution with different incident angles, especially with different wedge angles of the non-paralleled thin-film filter has been analyzed theoretically. The calculation and experimental results show that the transmitted-intensity distribution, transmitted-peak and the rectangle degree are greatly influenced by the wedge angle, the incident angle and the polarity of the wedge angle. In order to get stable transmitted-characteristics and high rectangle degree, the parallelism of the angle-tuned thin-film filter should be improved in fabrication.