Abstract: Disclosed herein is a system and method for measuring radiation temperature through filtration of optical error sources, which can measure surface temperatures of a heating substance within a heating furnace. The system comprises a front lens to collect infrared rays from a measuring target and from surroundings, a pin hole plate having a pin hole formed therein to allow only the infrared rays emitting from the measuring target area to pass therethrough, a rear lens to convert the infrared rays having passed through the pin hole into horizontal infrared rays, a condenser lens to collect the infrared rays having passed through the rear lens, and a radiation pyrometer to measure a temperature of the infrared rays having passed through the filtering unit. The system possible can ensure accuracy and reliability in temperature measurement, and can provide highly precise combustion control, operation stability, and improvement in quality of products.