CF<sub>2sub>H-substituted pyrazolines were synthesized by [3+2] cycloaddition between in situ generated CF<sub>2sub>HCHN<sub>2sub> and electron-deficient alkenes. The representative CF<sub>2sub>H-substituted pyrazoline was easily oxidized into the CF<sub>2sub>H-substituted pyrazole, which are important in agrochemistry.