Penetration experiments were conducted for several typical cylindrical-nose-tip projectiles (CNTP) into concrete targets with the compressive strengths of 9.0,28.4 MPa. The penetration mechanism was elementarily obtained by observing the recovered projectiles and the post-test targets. Thereby,a dimensionless parameter S2 was proposed to describe the target strength degradation and a parameter bt was brought forward to picture the cylindrical penetration pore radius. And then,the two parameters were introduced into the penetration formula by Forrestal et al to develop a new theoretical model for the penetration of CNTP into concrete. For the 28.4-MPa-strength concrete,the theoretical predictions by the new model agree well with the experimental data. For the 9.0-MPa-strength concrete,the theoretical predictions do not accord well with the experimental data but can still reflect the penetration mechanism of CNTP. Finally,two approaches were put forward for the penetration improvement of CNTP by decreasing S2 and increasing bt.