A nasal aspirator,: the nasal aspirator comprises a casing, a lower suction nozzle, an upper suction nozzle, a liquid storage cup and an air pump unit; the lower suction nozzle is disposed on an upper end of the casing, the lower suction nozzle has a chamber and a suction passageway therein, the chamber has an opening facing upward, an upper end of the suction passageway communicates with the chamber; the upper suction nozzle is mounted to an upper end of the lower suction nozzle, the upper suction nozzle includes a main body shell, an inner tube and an outer tube, a lower end of the main body shell is hermetically connected to the upper end of the lower suction nozzle, the main body shell has a cavity with an opening facing downward, the cavity communicates with the chamber, the inner tube extends from a top wall of the cavity, the inner tube has a first passageway, the outer tube extends upward from an upper end face of the main body shell, the outer tube has a second passageway, the second passageway communicates with the first passageway; the liquid storage cup is placed in the chamber and the cavity, the liquid storage cup includes a cup body and a cup cover, the cup body has an accommodating chamber with an opening facing upward, the cup cover is disposed on the cup body to cover the opening of the accommodating chamber, the cup cover is formed with a mounting hole, the inner tube passes through the mounting hole and extends into the accommodating chamber; the air pump unit is disposed in the casing, an air intake end of the air pump unit communicates with a lower end of the suction passageway, the air pump unit has a motor, wherein the lower suction nozzle has a first boss extending from a bottom of the chamber, and the lower suction nozzle further has a connecting tube extending downward from a bottom of the lower suction nozzle, and the suction passageway is formed in the first boss and the connecting tube, characterized in that the cup cover is formed with a through hole, the through hole communicates with the accommodating chamber and the cavity, an outer wall of the inner tube is hermetically mated with an inner wall of the mounting hole; the nasal aspirator comprises a control board, the control board is disposed in the casing; a detection system for detecting a liquid is provided in the chamber, the detection system is connected to the control board, and the motor is connected to the control board; and the cup cover is coupled to the cup body, a positioning post extends upward from an upper end of the cup body, the cup cover has a positioning hole, and the positioning post is inserted through the positioning hole and extends out of the cup cover. the air pump unit is disposed in the casing, an air intake end of the air pump unit communicates with a lower end of the suction passageway, the air pump unit has a motor, wherein the lower suction nozzle has a first boss extending from a bottom of the chamber, and the lower suction nozzle further has a connecting tube extending downward from a bottom of the lower suction nozzle, and the suction passageway is formed in the first boss and the connecting tube, characterized in that the cup cover is formed with a through hole, the through hole communicates with the accommodating chamber and the cavity, an outer wall of the inner tube is hermetically mated with an inner wall of the mounting hole; the nasal aspirator comprises a control board, the control board is disposed in the casing; a detection system for detecting a liquid is provided in the chamber, the detection system is connected to the control board, and the motor is connected to the control board; and the cup cover is coupled to the cup body, a positioning post extends upward from an upper end of the cup body, the cup cover has a positioning hole, and the positioning post is inserted through the positioning hole and extends out of the cup cover.