PT. XYZ is a textile company (spinning yarn) that produces several semi-finished products in the form of cotton yarn, polyester, viscone rayon, and many more. This company has several problems in its business processes. The problem that arises is the unclear Standard Operating Procedure (SOP) that the company has set which causes errors or disturbances in the production process. Another problem is the presence of a defective final product. For this reason, it can be seen the problems in the system that have been running so that improvements need to be made so that the problems that occur can be overcome by methods that can be used to control production quality, namely by using Failure Mode and Effect Analysis (FMEA), and Fault Tree Analysis (FTA). The conclusion of this study is the calculation using the FMEA method and processing using the FTA method, obtained several suggestions for the root cause of each problem that exists. There factors that cause defects that cause Non-Conforming Product (NCP) are humans, method, material, machine and environment factors. The proposed improvement to reduce product defects is to apply the proposed improvement which has been processed using the FTA methodPT. XYZ is a textile company (spinning yarn) that produces several semi-finished products in the form of cotton yarn, polyester, viscone rayon, and many more. This company has several problems in its business processes. The problem that arises is the unclear Standard Operating Procedure (SOP) that the company has set which causes errors or disturbances in the production process. Another problem is the presence of a defective final product. For this reason, it can be seen the problems in the system that have been running so that improvements need to be made so that the problems that occur can be overcome by methods that can be used to control production quality, namely by using Failure Mode and Effect Analysis (FMEA), and Fault Tree Analysis (FTA). The conclusion of this study is the calculation using the FMEA method and processing using the FTA method, obtained several suggestions for the root cause of each problem that exists. There factors that cause defects that cause Non-Conforming Product (NCP) are humans, method, material, machine and environment factors. The proposed improvement to reduce product defects is to apply the proposed improvement which has been processed using the FTA method.