The invention discloses a composite 
metal photocatalysis system which is represented by Ni-M-X-Y-Z, wherein M is selected from the group consisting of Al, Ag, Bi, Cd, Ge, Sb and Sn; x is selected fromthe group consisting of 
triphenylphosphine, triethylphosphine, tributylphosphine, tri-tert-butylphosphine and 
tricyclohexylphosphine; Y is selected from the group consisting of carbon nanorods, molecular sieves, ordered 
mesoporous carbon and 
silicon dioxide; Z is selected from the group consisting of 
diphenyl disulfide, 
dicumyl peroxide, hydrazine and 2,4-dinitrophenylhydrazine; the 
mass fractionof Ni is 10-20%; the 
mass fraction of M is 20-30%; the 
mass fraction of X is 20-40%; the 
mass fraction of Y is 15-40%,; and the 
mass fraction of Z is 10-30%. The catalytic 
system is used for preparing 1,1,2,3,3-pentamethylindane through free radical 
cycloaddition of alpha-methylstyrene and 2-methyl-2-
butene, an conversion rate is larger than 90%, and selectivity is larger than 85%; and a catalystis stable and not prone to loss in the free radical 
cycloaddition reaction. A method provided by the invention is easy to operate and good in economic benefit.