The embodiment of the invention provides a 
flash memory unit for a shared source line and a forming method thereof. The provided 
flash memory unit for the shared source line comprises a 
semiconductor substrate, a source line, a floating 
gate dielectric layer, a floating gate, a control 
gate dielectric layer, a control gate, side wall 
dielectric layers, side walls, a tunneling 
oxide layer, a word line, a drain 
electrode and a source 
electrode, wherein the source line is positioned on the surface of the 
semiconductor substrate; the floating 
gate dielectric layer, the floating gate, the control gate 
dielectric layer and the control gate are sequentially positioned on the surface of the 
semiconductor substrate on two sides of the source line; the side wall 
dielectric layers are positioned between the source line and the floating gate as well we between the source line and the control gate; the side walls are positioned on the floating gate and the control gate, which are far from the source line; the tunneling 
oxide layer is adjacent to the side wall and is positioned on the surface of the semiconductor substrate; the word line is positioned on the surface of the tunneling 
oxide layer; the drain 
electrode is positioned in the semiconductor substrate at one side of the word line, which is far from the source line; the source electrode is positioned in the semiconductor substrate which is right opposite to the source line; and the floating gate is provided with a p-type 
doping end which is close to the source line, wherein the 
doping type of the floating gate is in a p type and the 
doping type of other parts is respectively in an n type.