The invention provides a styrene butadiene styrene (SBS) modified bituminous waterproof sheet material and preparation technology thereof. The waterproof sheet material comprises polyester cloths, an immersion oil coating layer and a film-mulching layer. The immersion oil coating layer comprises the following materials in parts by mass: 32-52 parts of bitumen, 12-22 parts of residual oil, 9-19 parts of EPDM rubber powder, 2-7 parts of butyl rubber powder, 11-21 parts of talc powder and 5.6-10.6 parts of SBS rubber. The bitumen is the mixture of 9-19 parts of 10# bitumen and 23-33 parts of 60#bitumen. The invention is characterized by wide high temperature and low temperature resistance range, good elasticity and good hardness, is not easy to deform and is suitable for various levels of waterproofing works of roofing of industrial and civil buildings, underground, bridges, highways, swimming pools and the like in the south and in the north.