A rapid assembly and automatic sampling drilling tool for frozen soil layer exploration includes a fixed flow divider, a flow guide pipe, a coring pipe and a drill bit. The fixed flow divider is connected to the drill bit through the flow guide pipe and the coring pipe mounted between the fixed flow divider and the drill bit. Two ends of the flow guide pipe communicate with the fixed flow divider and a main flow channel in the drill bit respectively. Hot water in the fixed flow divider can be conveyed into the drill bit through the flow guide pipe and sprayed from a nozzle arranged on the drill bit for drilling and coring operations. An inlet of the coring pipe communicates with a coring channel in an inner cavity in the drill bit, and a core sample drilled by the drill bit is taken out through the coring pipe.