Abstract: Having a new generation of selective laser melting process, surface exposure selective laser melting technology has the advantages of high forming efficiency and uniform temperature field, and is becoming a research focus in additive manufacturing field. The influence of laser spot overlap rate and electric current on the shape accuracy of single-layer laser melting with surface exposure was investigated. The effects of overlap rate, exposure time and electric current on the forming of laser spot, track, circular ring and sharp angle were studied by the control variable method. The experimental results show that: within a certain range, the larger the electric current is, the more uniform the laser spot is, and the more conducive to forming; The lowest shape error can be obtained with overlap rate of 38.4%. The forming error of the circular ring increases with the increase of electric current. The forming error of sharp angle increases first and then decreases with the increase of electric current. The shape error caused by zero-order diffraction can be reduced when the overlap rate is 46.1% and 38.4%.