One of the most important issues in production planning is to reduce waste materials as much as possible. This helps reduce all necessary expenses and increase productivity and efficiency. This paper presents an empirical investigation to find important factors for reaching lean production planning. The proposed study determines nine different factors including information technology, organization and leadership, human resources development, inventory management, total quality management, process management, equipment management, maintenance engineering. In order to find out the effects of these factors, the study designs a questionnaire and distributes it among some managers in producer of radiator in Iran. Cronbach alpha is equal to 0.86, which validates the questionnaire. Using some statistical observations, the study has confirmed that all mentioned factors influences production planning, positively.