The disclosure discloses a video bit rate control method and a video coding device. The method includes: according to a pre-set first bit rate value and a code size generated in a previous period of time, a first quantization parameter is generated (S1); according to a pre-set second bit rate value and the code size generated in the previous period of time, a second quantization parameter is generated (S2); the first quantization parameter is composed with the second quantization parameter (S3); if the first quantization parameter is greater than or equal to the second quantization parameter, an image frame in a current period of time is coded by using the first quantization parameter (S4); and if the first quantization parameter is less than the second quantization parameter, the image frame in the current period of time is coded by using the second quantization parameter (S5).