The invention discloses a coal gasification-to-synthesis gas and chemical chain-to-oxygen-hydrogen combined cycle apparatus and a coal gasification-to-synthesis gas and chemical chain-to-oxygen-hydrogen combined cycle method. With the apparatus and the method of the present invention, the high investment and the high energy consumption deep-cooling air separation oxygen production unit are eliminated, and the system efficiency is beneficially improved. Compared to the traditional coal gasification-to-hydrogen apparatus, the apparatus of the present invention has the following advantages that only three processes such as gasification, combustion and water decomposition hydrogen production are required to be performed, such that the process is simple; the H2 purity is substantially increased and is up to more than 99%; the high purity CO2 capture is achieved so as to substantially reduce the CO2 emission; the high purity O2 is produced, the purity is much higher than the oxygen produced through the deep cooling air separation, and the purity of the prepared synthesis gas is higher than the purity of the synthesis gas prepared by the traditional coal gasification apparatus; the apparatus of the present invention is adapted to the variable load operation of the coal gasification furnace; when the apparatus works in the pressurization state, the pressure can be determined according to the requirement of the gasification furnace, such that the purities of the produced CO2, the produced O2 and the produced H2 cannot be affected; and the ratio of the synthesis gas to the H2 can be flexibly adjusted.