AlCrTiWNbTa multielements high entropy alloy films have been synthesised by using magnetron co-sputtering of three binary alloy targets. Effects of substrate bias on the microstructure and mechanical properties of the films are studied. The composition and the crystallographic structure of the films are characterised by an electron probe microanalyser (EPMA) and an X-ray diffractometer respectively. The surface micrographs of the films are described by atomic force microscope (AFM). The microhardness and elastic modulus of the films are measured using a nanoindenter. It is found that the deposition rate of the AlTiWTaNbCr films decreases as the increase in the bias voltage. The microstructure of the deposited films is amorphous. The microhardness and elastic modulus of the films keep at about 12.5 and 180 GPa respectively. The surface roughness is in the range of 0.3-0.5 nm.