The key technology of the film design and fabrication is the non-destr uctive measurement of the thickness of nano-metal films,and the measurement of the thickness of non-precious metal films is particularly difficult.In this pa p er,the long-range surface plasmon wave is first proposed base on prism-math l iq uid-metal film-substrate glass configuration by mid-infrared laser of the 3.39μ m laser wavelength.we have compareed the half widths of attenuated total reflec tion of surface plasma wave and long-range surface plasma wave by calculating. T he results of calculation indicate that the half width of long-range surface pl a smon wave is only 4.7% of surface plasmon wave,which can effectively improve th e sensitivity of non-precious metal films measurement.The experimental results indicate that the variation curve of the minimum attenuated total reflection abs orption peaks related to different ferrum film thickness have a good linearity i n the range of 10－90nm,and the measuremental resolution can reach 1nm.The thi c kness of other non-noble metal films can be measured by changing the thickness a nd refractive index of the matching liquid,which greatly expands the applicatio n scope by using this measuremental method.It will provide a new technical meas uremental method in the fields of nano-sacle non-precious metal film thickness es.