The effect of five different kinds of pipes on viscocisy loss of polyacrylamide displacing agent with the concentration was studied in this paper. The results showed that the seamless steel pipe of 20# and the pipe with corrosion protective coating had greater influence on the viscosity loss of polyacrylamide displacing agent, and the viscosity loss rate could reach 60% and 10%, respectively. While GFRP pipe, flexible composite pipe for high pressure and 0Cr18Ni9 stainless steel pipe had smaller influence on the viscosity loss, and the viscosity loss rate was less than 3%. With the higher concentration of polyacrylamide, the viscosity increased and the effect of pipe material on viscosity and the viscosity loss rate tended to be smaller