Alga taking system and method of spirulina culture machine

The invention provides an alga taking system and an alga taking method of a spirulina culture machine. The alga taking system comprises a disinfection cabinet, an alga filtering cup, a box body, a cover body, a built-in light transmitting plate, an alga taking device, a diaphragm pump, a filter head, a liquid transportation pipe, an observation window and an alga taking reference column; the alga taking reference column is vertically arranged at the bottom of the box body; the diaphragm pump is located in a cavity composed of the cover body and the built-in plate; the alga taking device comprises a top cover, a liquid collection pipe and a cup type filter screen; the cup type filter screen comprises a cup body and a filter screen; the filter screen is stuck on an inner wall of the cup body; a second liquid inlet hole is formed in the upper side of the cup body and a cup edge is arranged at the top of the cup body; through holes are formed in the bottom and the outer side of the cup body; a first liquid inlet