An optical accessible constant volume combustion bomb was developed by the modular design concept to improve its adaptability and capability. This combustion bomb can meet the requirements for premixed combustion, spray evaporation, spray combustion, etc. To simulate the high pressure, high temperature and oxygen lean conditions occurred in advanced diesel engines, the ambient gas in the combustion bomb was heated by preburning of acetylene+oxygen mixture. Experiments show that this apparatus can simulate different spray combustion environments conveniently, the oxygen concentration ranges from 0% to 21%, the ambient pressure ranges from 0.04 to 10.00 MPa and the ambient tempreature ranges from 300 to 1300 K. Spray atomization, evaporation and combustion process were studied in the apparatus using high speed schlieren method. Results show that this apparatus provides an essential prerequisite for studying issues related to vaporizing and combustion fuel spray in internal combustion engines.