Empty needle with filtering function

The utility model discloses an empty needle with a filtering function, belongs to the field of medical instruments, and aims to solve the problem of how to prevent foreign matters from entering a liquid bag or the body of a patient along with liquid medicine. According to the empty needle, a first channel serving as a liquid inlet channel and a second channel serving as a liquid outlet channel are arranged in a closed end, a filtering device is arranged on the second channel, and meanwhile a switching mechanism is arranged in the closed end; when a nurse sucks liquid medicine through the empty needle, the liquid inlet and outlet channel can be communicated with the first channel through the switching mechanism, and smooth suction of the liquid medicine can be guaranteed; when a nurse injects liquid medicine through the empty needle, the liquid inlet and outlet channel can be communicated with the second channel through the switching mechanism, it can be guaranteed that the dissolved liquid medicine is smoothl