NOVELTY - Integrated biodiesel oil system comprises a dehydrating device (1), water circulating negative pressure device (2), a reaction device (3) and a separating water washing device. The dehydrating device comprises a first liquid holding container (11) and a first heater (12) to heat the first liquid holding container. The water circulation negative pressure device comprises a cooling circulating pipe, a second liquid holding container and a circulating water pump. The cooling circulating pipe is connected with the second liquid holding container and the first liquid holding container.    USE - The system is useful for preparing laboratory biodiesel.    ADVANTAGE - The system improves the quality of biodiesel oil.    DETAILED DESCRIPTION - Integrated biodiesel oil system comprises a dehydrating device (1), water circulating negative pressure device (2), a reaction device (3) and a separating water washing device. The dehydrating device comprises a first liquid holding container (11) and a first heater (12) to heat the first liquid holding container. The water circulation negative pressure device comprises a cooling circulating pipe, a second liquid holding container and a circulating water pump. The cooling circulating pipe is respectively connected with the second liquid holding container and the first liquid holding container. The circulating water pump is installed on the cooling circulating pipe. The reaction device comprises a third liquid holding container and a second heater to heat a third liquid holding container, a first oil pump and the first oil pipe for conveying the oil. The first oil conveying pipe is inserted into the first liquid holding container and connected with the third liquid holding container. The first oil pump is installed on the first oil conveying pipe. The separating water washing device comprises a second oil pipe and the third oil pipe, an oil return pipe, a separator, a second oil pump, a third oil pump and a container. The second oil pipe is inserted into the third liquid holding container and is connected with the separator. The second oil pump is provided with the second oil. The separator is connected with the container. The oil return pipe is connected with the container and the first liquid holding container. The third oil pump is provided with the oil return pipe. The third oil pipe is provided with a valve. The third oil pipe is respectively connected with the first oil pump and the separator.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of the integrated biodiesel oil system.    Dehydrating device (1)    Water circulating negative pressure device (2)    Reaction device (3)    First liquid holding container (11)    First heater (12)