Abstract: This paper studies the influence of magnetorquer on the space plasma and presents calculations of the motion states of plasma in the magnetic field produced by the magnetorquer in operation, and the electron density distribution around the magnetorquer. The results show that the electron density around the magnetorquer will increase during the operation of the magnetorquer. The axial dimension of the region with increased electron density is a little larger than the length of magnetorquer. In the region, the electron density is 2-5 times higher than the value when the magnetorquer is not in operation and even 10 times in some places.