The main purpose of manufacturing industry is to produce goods economically in order to gain profit and be able to deliver products on time. Ineffective and efficient production processes lead to non-current production. Lean production systems help companies to be competitive, especially in terms of reducing waste (waste) that occurs in their operations. This study aims to reduce production waste in one automotive company by using Waste Relationship Matrix (WRM), Waste Assessment Questionnaire (WAQ) and Value Stream Mapping (VSM). Activities in the automotive Industry is to design, develop, manufacture, market and sell motor vehicles in the world. The three methods are intended to identify and analyze the waste (waste) that occurred and make improvements to eliminate waste. From the research results obtained type of waste "form" is waiting and motion. While the type of waste "to" the inventory. The three types of waste is the greatest procession to occur in the process of assembly trimming on the production line of Daihatsu SIGRA 1.5 L 3NR-Ve, DOHC Dual VVT-i at PT. Astra Daihastu Motor. Then performed the improvement implementation by using WRM and VSM method obtained the results of waste efficiency that occurs in the type of waste from the motion from 17.65% to 15.75%, waiting from 15.88 to 13.12%, and lead time down from 14.202 minutes to 12.322 minutes in one assembly process trimming. Some suggestions for improvements made are the implementation of the FIFO system (First in First Out), Improving changes in movement and movement of workers, and line balancing on the assembly line trimming process lines of automobile production processes.