I In carrying out the production process, PT. XYZ cooperates with many vendors to make parts, because the company does not have the technology to manufacture these parts. With the aim of cost minimization and easier quality control. Currently the number of parts supplied by vendors is approximately 9000 part numbers from 210 vendors. Because quality assurance uses a sampling system, it is not possible to ensure all delivery vendors are on time, and the vendor selection process is based solely on price. So it is necessary to evaluate and improve the performance of vendors. The purpose of this study is to create: a vendor performance evaluation assessment model, a vendor evaluation audit model, and a control model for improving audit results with statistical process control (SPC). This study produces a performance evaluation assessment model with 3 main criteria of quality, delivery, and service, and this model also recommends the type of audit that needs to be carried out. The vendor evaluation audit model is divided into 3 types according to the assessment criteria, with the aim of making the audit process more detailed and shortening the audit time. The results improvement control model with SPC provides information to the auditor regarding the results of the improvements that have been carried out properly and are running stable or not.