A drug infusion flow regulating apparatus comprising: an inlet configured to receive liquid into the apparatus, an outlet configured to discharge the liquid from the apparatus, a cylinder assembly comprising a first cylinder, a second cylinder and a third cylinder that are arranged substantially coaxially along an axial direction, the first cylinder comprising a first interior surface, a continuous spiral thread formed into the first interior surface of the first cylinder, the second cylinder being fitted into the first cylinder and comprising a second interior surface and a second exterior surface, a spiral liquid-flow channel formed between the first cylinder and the second cylinder through the continuous spiral thread, the spiral liquid-flow channel being in fluid communication with the inlet, a plurality of longitudinal grooves extending substantially parallel to the axial direction and formed into the second cylinder on the side of the second interior surface, a plurality of through-holes formed in the second cylinder and in fluid communication with the spiral liquid-flow channel, the third cylinder being fitted into the second cylinder and comprising a third exterior surface, a plurality of independent liquid-flow passages formed between the second cylinder and the third cylinder, each of the plurality of independent liquid-flow passages being in fluid communication with the spiral liquid-flow channel via at least one of the plurality of through-holes, a diaphragm valve configured to regulate fluid communication between the spiral liquid-flow channel and the outlet, two immediately neighboring liquid-flow passages being liquid-tightly separated from each other by close contact between the second interior surface and the third exterior surface, a fourth cylinder received within the third cylinder and rotatable relative to the third cylinder, at least one of the plurality of passages forming a fluid channel extending to the diaphragm valve depending upon a rotational position of the fourth cylinder relative to the third cylinder, the diaphragm valve comprising a deformable diaphragm and a valve seat that are received in an interior space of the fourth cylinder, the deformable diaphragm dividing the interior space into a first chamber and a second chamber, the inlet being fluidly connected to the first chamber, and the outlet being fluidly connected to the second chamber, the diaphragm being configured to deform toward the valve seat and recover away from the valve seat in response to the pressure differential between the first and second chambers. an inlet configured to receive liquid into the apparatus, an outlet configured to discharge the liquid from the apparatus, a cylinder assembly comprising a first cylinder, a second cylinder and a third cylinder that are arranged substantially coaxially along an axial direction, the first cylinder comprising a first interior surface, a continuous spiral thread formed into the first interior surface of the first cylinder, the second cylinder being fitted into the first cylinder and comprising a second interior surface and a second exterior surface, a spiral liquid-flow channel formed between the first cylinder and the second cylinder through the continuous spiral thread, the spiral liquid-flow channel being in fluid communication with the inlet, a plurality of longitudinal grooves extending substantially parallel to the axial direction and formed into the second cylinder on the side of the second interior surface, a plurality of through-holes formed in the second cylinder and in fluid communication with the spiral liquid-flow channel, the third cylinder being fitted into the second cylinder and comprising a third exterior surface, a plurality of independent liquid-flow passages formed between the second cylinder and the third cylinder, each of the plurality of independent liquid-flow passages being in fluid communication with the spiral liquid-flow channel via at least one of the plurality of through-holes, a diaphragm valve configured to regulate fluid communication between the spiral liquid-flow channel and the outlet, two immediately neighboring liquid-flow passages being liquid-tightly separated from each other by close contact between the second interior surface and the third exterior surface, a fourth cylinder received within the third cylinder and rotatable relative to the third cylinder, at least one of the plurality of passages forming a fluid channel extending to the diaphragm valve depending upon a rotational position of the fourth cylinder relative to the third cylinder, the diaphragm valve comprising a deformable diaphragm and a valve seat that are received in an interior space of the fourth cylinder, the deformable diaphragm dividing the interior space into a first chamber and a second chamber, the inlet being fluidly connected to the first chamber, and the outlet being fluidly connected to the second chamber, the diaphragm being configured to deform toward the valve seat and recover away from the valve seat in response to the pressure differential between the first and second chambers.