The invention discloses a multihole cathode additional magnetic field plasma power thruster. After being sleeved by an insulating sleeve, a cathode portion composed of a multihole structure cathode, two cathode connecting members and a tail end cap is connected with a left end face of a middle connecting member through an insulating bush and a tail screw; an anode portion composed of an anode, an anode bush and an anode shell is connected with a right side face of the middle connecting member through an anode retaining ring and an anode screw; two air incoming passages which are communicated are arranged on the middle connecting member, and air incoming is realized through the air incoming passages. Consequently, propellant is divided into three parts for supplying, two parts reach the anode through two air pipelines and the air incoming passages respectively, and the other part reaches the anode through the cathode connecting members and the inside of the cathode. An annular additional magnetic coil sleeves outside the thruster. Requirements, of the thrust, on electron emitting capacity under a high-power condition are met; due to increase of effective sectional area of the cathode, reliability of the cathode is improved, and service life of the cathode is prolonged.