Abstract: Taking the tomato (Solanum lycopersicum) cultivar “Kuiguan108” as test object, a comparative study was made on the effects of outer type and built-in type straw bio-reactors on the CO₂ concentration, air relative humidity , air vapor pressure deficit in the solar greenhouse during the tomato growth over autumn-delayed cultivation as well as the effects of the bio-reactors on the tomato growth and photosynthetic performance. As compared with that in CK, the average CO₂ concentration in the greenhouse with outer type straw bio-reactor at 9:30-11:30 and 14:30-15:00 on sunny days was increased significantly by 207.3 and 103 μmol·mol^-1, respectively, and the average CO₂ concentration in the greenhouse with built-in straw bio-reactor at 9:30-11:30 on sunny days was raised by 19.0 μmol·mol^-1. Both the outer type and the built-in type straw bio-reactors promoted the tomato plant height growth and early flowering, enhanced the plant net photosynthetic rate  and the yield per plant and per unit area significantly, and decreased the plant transpiration rate at the stages of vegetative growth and fruit bearing significantly. Nevertheless, as compared with built-in type straw bio-reactor, outer type straw bio-reactor was more suitable for the autumn- delayed cultivation of tomato in solar greenhouse.