Abstract: The CL reactions of Sr(~1S), Sr(~3P)+Cl_2 have been studied under single collision condition on a beam-gas apparatus in the pressure of range 10~(-5)—10~(-4) Torr.The temperature of the metal oven was about 1000 K. The CL spectra of SrCl (A,B) and SrCl_2~* produced in the reactions of Sr, Sr~* +Cl_2 have been observed and analyzed. The CL spectra are always dominated by the monochloride emission while the subcontinuous emission of dichloride SrCl_2~* becomes stronger with increasing Cl_2 pressure. The experimental results show that the intensity of SrCl~* emission depends linearly upon both Cl_2 pressure and Sr number density. This means that SrCl~* is the direct product of single collisions. Whereas the quadratic dependency of SrCl~*_2 intensity upon the Cl_2 pressure shows that it is produced in arreaction of SrCl+Cl_2, the same mechanism as BaCl~*_2 produced in reaction of Ba+Cl_2~([4,5]). The total cross section for the removal of metal atoms in ground state Sr(~1S) and excited states Sr(~3P) by Cl_2 molecules are 5.8 nm~2 and 9.7 nm~2 respectively. The relative photon yield of SrCl(nm) produced by Sr(~1S) and Sr(~3P) reacting with Cl_2 is about Φ~*/Φ~0=115.