Finite element software ANSYS is used to simulate laser straight welding one dimensional ZnO with diameter from 200 nm to 1000 nm and 5 μm length,the distribution of temperature and melting pool is obtained.For one dimensional ZnO with 500 nm diameter,the laser power should be increased by 0.5 time as welding time was reduced to half in order to form different depth of melting pool at the joint.The situation in which diameters of one dimensional ZnO and defocus distance of the focus points are different is simulated to form the 50% interface area of the melting pool.The needed power exponentially decays and the needed welding time exponentially grows as the material′s diameter increases.No matter positive or negative defocus,with the increase of the defocus distance the needed laser power increases evidently as the diameter of ZnO decreases.In the case of negative defocus,with the increase of the focus distance,the needed laser welding time falls remarkably as the diameter of ZnO increases,however,in the case of positive defocus,the needed welding time almost unchanged.