A micro calorimetry based on interferometer to measure the light-induced reaction volume and quantity of heat is studied. The principle to get the reaction volume and quantity of heat is introduced. The method is used to investigate the reaction of myoglobin (Mb) with CO after light excitation. Accompanying the reaction of Mb with CO, the quantity of heat and reaction volume are changed which could lead to the variation of the index of refraction of Mb. The thermodynamic information could be obtained through measuring the phase variation. The experiment to get the reaction volume and quantity of heat for the reaction of Mb with CO is done at 273 K to 301 K with a time window of 10-6 s to 10-1 s. The measured reaction enthalpy is 80 kJ/mol, the reaction volume is 10 mL/mol.