We theoretically investigated negative entropy S of biopolymer which passes through a nanometer pore(such as α-hemolysin), especially entering process and escaping process, on the basis of which we also studied biopolymer entering-pore time τent, biopolymer entering mean velocity vent, biopolymer escaping-pore time τesc, and biopolymer escaping mean velocity vesc, respectively. Our results illustrate that the entering and escaping processes of biopolymer depend on its negative entropy, and entering process is more difficult than escaping process for biopolymer translocation. This tremendous difference between the two processes will offer a useful engineering hint for single macromolecule identification.