Brominated flame-retardants (BFRs) were widely used for being high cost effective. However, due to the environmental concerns of BFRs, new flame-retardants with similar flame inhibition mechanism (gas phase combustion inhibition) need to be developed and tested for fire resistance. The current method for laboratory testing of fire resistance is on bench-scale Cone Calorimeter. This test requires relatively large samples and is extremely expensive for developing new materials. An innovative instrument called the Flaming Combustion Calorimeter (FCC) was designed, built and implemented to measure the heat release rate of flaming combustion of milligram-scale sample and the test result showed the FCC is able to detect the gas-phase combustion inhibition mechanism of bromine with good sensibility and repeatability.