The crystal structure of the title compound 2-ethoxycarbonylmethyl-8-chloro-3a,4-dihydro-3a-methyl-chromeno[4,3-c]pyrazol-3（2H）-one（C15H15ClN2O4,Mr = 322.74） has been prepared and determined by single-crystal X-ray diffraction.The crystal is of orthorhombic,space group Pccn with a = 16.7246（10）,b = 19.6626（12）,c = 9.3013（6） ,V = 3058.7（3） 3,Z = 8,Dc = 1.402 g/cm3,μ = 0.269 mm-1,F（000） = 1344,the final R = 0.0506 and wR = 0.1464 for 2568 reflections with I 〉 2σ（I）.In addition,disordered C（14） and C（15） atoms exist in the crystal structure.
