A channel estimation method and a channel estimation system based on time-domain training sequence are provided. The channel estimation system first acquires an initial channel vector used for channel estimation of a current frame, and calculates an algorithm initial vector based on a training sequence vector contained in a received receiving signal vector and the receiving signal vector, then performs estimation based on the initial channel vector and the algorithm initial vector and using a conjugate gradient method based on a preprocessing matrix to acquire each channel estimation value, and eventually perform noise reduction processing on each channel estimation value based on a first predetermined threshold value to acquire a final channel estimation value. Compared with the existing channel estimation methods, the present invention has a shorter delay and lower calculation complexity, and thus can be easily implemented.