1. To further evaluate the safety and efficacy of PEG-Somatropin in the treatment of children with growth hormone deficiency for a relatively long period
2. To explore the factors influencing the efficacy of PEG-Somatropin and to establish the height prediction model based on Chinese children with short stature, and to provide the basis and guidance for standard and reasonable long-term clinical application of PEG-Somatropin.

Inclusion Criteria:

• Children has completed all visits and therapy in previous phase IV study;
• Investigators evaluate subjects could continue growth hormone therapy;
• Subjects is willing and able to cooperate to complete scheduled visits, treatment plans and laboratory tests and other procedures, to sign informed consent.

Exclusion Criteria:

• Children with epiphyseal closure;
• Children is near the adule final height, that is, growth rate≤ 2 cm / year or bone age ≥ 14 years old for girls, bone age ≥ 16 years old for boys;
• Dysfunction of liver and kidney (ALT> 2 times the upper limit of normal, Cr> upper limit of normal);
• Patients with known hypersensitivity to PEG-Somatropin or Somatropin or any other components of the study product;
• Patients with severe cardiopulmonary or hematological diseases, a current or past history of malignant tumors, immunodeficiency diseases, or mental diseases;
• Patients with diabetics;
• Patients with congenital bone dysplasia or scoliosis;
• Patients took drugs that would influence the efficacy and safety of PEG-Somatropin after phase IV study and before screening for this extension study;
• Other conditions in which the investigator preclude enrollment into the study.