Abstract: We believe there are some deficiencies in the design of the MW50/28-298-type gas aetylene and amonia compressor with oil-free lubrication,for example lower air discharging capacity and short service life.Hence,we propose reforming the oil-free lubrication and piston structure of the gas aetylene and amonia compresso with theoretical and experimental analysis.The experimental results show that a small quantity of lubrication oil contained in the compressor thus reformed has no influence on the mixed gas quality and that the reformed compressor's performance is better than that of the existing design;thus its service life is greatly enhanced.