The objective of this project was to establish analytical method for heating value in flare stacks for EPA to establish the standard operation procedure. The heating values in flare stacks were measured by stoichiometric combustion method based on ASTM D4891. Stoichiometric combustion method burned the mixture of sample gas, air, and fuel, and then calculated the heating values depending on the temperature variation of combustion. For the stability of the stoichiometric combustion system, one hour warming up time was required before continuous monitoring heating values. Afterwards, ninety-second reading time rule for each calibration points, zero and span, was required for obtaining reliable data, and the total time was about 5 minutes. The standard methane gas (5% to 100%), theoretically resulting in 46 to 1012 BTU/ft3 after combustion, was used to make the calibration curve. The ratios of measured value to theoretical value were between 90.91% to 99.41%, and the error was less than 10%. Based on methane’s experimental results, the accuracy of this analytical method for heating value using stoichiometric combustion method was 100.03±1.35%, and the precision was 0.68%. For all other experimental compounds, including ethylene, xylene, acetaldehyde, 1, 2-dichloroethane, hydrogen sulfide, and ammonia, the errors of the ratio of measured value to theoretical value were all within 20%. As for the high-heating-value waste streams due to abnormal emissions, one auto-dilution system for high-heating-value emissions was developed in this project to handle this abnormal situation. According to our experimental results using the standard calibration gas - 100% methane to simulate the abnormal situation, the measured values were 1010±24 BTU/ft3 and the accuracy of this auto-dilution system was better than 97%. As for field tests, based on our results of 7 sessions, the heating values measured by stoichiometric combustion method and by gas chromatography method had positive correlation. The errors of the ratio of heating values measured by stoichiometric combustion method to by gas chromatography method were within 20%. But the reasons causing the errors need to be further studied in the future. The results of this study suggested that the stoichiometric combustion method could be used for measuring heating values in flare stacks in petroleum plants. Besides, the results of this study could be used to establish standard operation procedure for EPA. To understand the difference of the measured values between by stoichiometric combustion method and by gas chromatography method, the composition of waste streams from different manufacturing processes and different flare stacks must and be studied in the future.