Recently a novel electric hammer driven by tubular permanent magnet linear synchronous motor (TPMLSM) has arouse great interest among researchers in the field of deep drilling for its distinctive advantages compared with hydraulic and pneumatic hammers. The working temperature in deep down-hole is relatively high, so the research of the influence of high temperature in deep hole on the electromagnetic thrust of the linear motor is very important. In this paper, a numerical electromagnetic calculation model of the thrust of the hammer was established to analyze the influence as a result of the loss of permanent magnet, coil resistance variation and coil volume expansion due to the temperature variation from 20°C to 300°C. The calculated results showed from 20°C to 300°C, the increase of the copper loss reduced the thrust by 31%, the loss of permanent magnets reduced the thrust by 18%. And the effect of the air-gap variation by thermal expansion can be neglected.