A miniature continuous-wave CO₂ laser is tuned to operated in -20 single spectrum lines from 9.23 to 10.65 μm, all these lines are converted respectively by a IR-nonlinear optical crystal of AgGaSe2 with size 8 mm×8 mm× 15 mm into the second harmonics. Second-harmonic output at 5.3μm of the order of 2.1 μW has been experimently obtained for the 10P(20) line, the external angular acceptance angle △θext · L is 2.1°·cm.