Hanil Jaya Steel company is engaged in reinforcing steel fins with various deformed and according to the Indonesian National Standard (SNI). The product produced by this company is Reinforced Iron or commonly known as Esser Concrete. One of the most important processes in the manufacturing stage of reinforcing steel is the Furnace Billet Reheating process to be processed into reinforcing steel. This study aims to analyze the performance of the reheating furnace on billet production of reinforcing iron in the Rolling Mill III area of PT. Hanil Jaya Steel. This study uses the observation method. This research results that RHF heating is carried out to change the material properties, and carry out the machining process (heat treatment). The type of furnace used at PT. Hanil Jaya Steel is a pusher type, the furnace is used to heat billets measuring 150 × 150 × 6000 mm with temperatures reaching 1100 ºC -1250 ºC. The nominal capacity of the furnace used is 30 tons/hour. The fuel used in the reheating furnace is natural gas from PGN. The process of making reinforced concrete steel, reheating furnace process is the initial process that must be carried out to change the billet into a material that is easily shaped into reinforcing steel according to SNI standards. Heating process billet is carried out by inserting billets one by one into the RHF with a temperature of up to 1100 ºC for 2 h. With this process the billet changes, which is useful for the next process, namely the rolling process.