A smoke generator using dry ice, comprising: a casing including a first chamber, a second chamber, and a third chamber, wherein the casing includes an outer side having a smoke outlet intercommunicating with the second chamber, wherein the first chamber includes a smoke discharge port intercommunicating with the second chamber, wherein the first chamber is configured to receive dry ice, and wherein the second chamber is configured to receive water; a separation member disposed between the first chamber and the second chamber and located below the smoke discharge port, wherein the separation member includes a water draining port intercommunicating with the first and second chambers, wherein the separation member is disposed inclinedly to locate the water draining port in a lowest location of the separation member; a water pump device fixed in the third compartment, wherein the water pump device includes a water inlet located in the second chamber and a water spraying end located in the first chamber, wherein the water pump device is configured to deliver water in the second chamber to the first; a heater disposed in the second chamber and configured to increase a temperature of the water; and a water discharge mechanism coupled to the separation member, wherein the water discharge mechanism includes a valve plate normally in a first position closing the water draining port; characterised in that the water discharge mechanism further includes a support spring biasing the valve plate to the first position, wherein the valve plate is movable between the first position closing the water draining port and a second position revealing the water draining port, wherein when a water level of the water in the first chamber rises to a height and imparts a load force to the valve plate to thereby overcome the support spring, the valve plate moves from the first position to the second position, and the water in the first chamber flows back to the second chamber. a casing including a first chamber, a second chamber, and a third chamber, wherein the casing includes an outer side having a smoke outlet intercommunicating with the second chamber, wherein the first chamber includes a smoke discharge port intercommunicating with the second chamber, wherein the first chamber is configured to receive dry ice, and wherein the second chamber is configured to receive water; a separation member disposed between the first chamber and the second chamber and located below the smoke discharge port, wherein the separation member includes a water draining port intercommunicating with the first and second chambers, wherein the separation member is disposed inclinedly to locate the water draining port in a lowest location of the separation member; a water pump device fixed in the third compartment, wherein the water pump device includes a water inlet located in the second chamber and a water spraying end located in the first chamber, wherein the water pump device is configured to deliver water in the second chamber to the first; a heater disposed in the second chamber and configured to increase a temperature of the water; and a water discharge mechanism coupled to the separation member, wherein the water discharge mechanism includes a valve plate normally in a first position closing the water draining port; characterised in that the water discharge mechanism further includes a support spring biasing the valve plate to the first position, wherein the valve plate is movable between the first position closing the water draining port and a second position revealing the water draining port, wherein when a water level of the water in the first chamber rises to a height and imparts a load force to the valve plate to thereby overcome the support spring, the valve plate moves from the first position to the second position, and the water in the first chamber flows back to the second chamber.