The invention discloses a method for producing coal tar and synthesis gas from oil-rich coal through a pyrolysis and gasification coupling device and an oil gas purification device. Oil-rich coal serves as the raw material, pyrolysis gas and rough synthesis gas are obtained through the pyrolysis and gasification coupling device firstly, and the two gases are collected respectively in one device; then, specific to the problems of difficult oil and gas separation, the low coal tar recovery rate and much produced waste water, the oil and gas purifying device is arranged, the coal tar is recovered in a dust and heat recovery mode, an oil gas separation mode, an oil solid separation mode and a low-temperature oil gas separation mode, a coal tar product is obtained, the recovery rate of the coal tar is increased, and the waste water discharging amount in the separation process is reduced. Meanwhile, the synthesis gas is further purified through units of transforming, low-temperature methanol washing and the like, and a synthesis gas product is obtained.