Objective: The objective of the study was to investigate the effect of multiple clinical parameters (age, weight, blood types, and bleeding types) on FVIII pharmacokinetic parameters (PK parameters) in adult patients with severe hemophilia A (SHA), draw up individualized preventive treatment plans, and observe clinical efficacy. Methods: Forty SHA patients treated in our hospital from January 2018 to May 2019 were enrolled, with their age, weight, blood types, bleeding types, and PK parameters measured to analyze the effects of clinical parameters on PK parameters. Individualized preventive treatment was developed, and patients were followed up for 1 year. The annual bleeding rate (ABR), annual joint bleeding rate (AJBR), and annual FVIII dosage were observed and compared before and after treatment. Results: Weight, blood types, and bleeding types could affect the PK parameters of FVIII. A prophylaxis plan was formulated under the guidance of FVIII half-life. After 1 year of follow-up, the mean ABR dropped from 36.54 to 4.06, decreased by 88.9%, the mean AJBR dropped from 28.36 to 2.75, decreased by 90%, and annual FVIII dosage increased by 47%. The dosage of FVIII in 8 patients after was less than that before prophylaxis, and the average half-life time of these 8 patients was 13.32 h. Conclusions: (1) Weight, blood types, and bleeding types of adult SHA patients could affect FVIII half-life. As body mass index increased, FVIII half-life was significantly prolonged. The FVIII half-life of patients with type O blood was significantly shorter than those with other blood types, and the FVIII half-life of knee joint bleeding was conspicuously shorter than those of elbow joint bleeding. (2) Individualized preventive treatment could markedly reduce the number of bleeds. For patients with a long half-life period, the total annual FVIII dosage could be reduced to achieve bleeding prevention.