The high-speed wire electrical discharge machining (WEDM-HS) machine has been more and more favoured by customers for the low manufacturing cost, the degree of automation and the advantages over the WEDM-LS in price performance ratio. However, the processing quality (the precision of form and position and the surface quality) of WEDM-HS is poorer than that of WEDM-LS, and the processing quality is one of the main technical indicators of WEDM. There are many factors on the processing quality of WEDM-HS, the effects of non-electrical parameters, including the machine precision, the wire-moving system and wire-moving way of the wire electrode and the working solution, on the processing quality of WEDM-HS are discussed, and the corresponding measures of improving the processing quality are put forward, which provide the sufficient basis for further improving the processing quality of WEDM-HS.