A technical measure for gel electrophoresis shaping that can make the gel electrophoresis generate no bubbles including in the gel, and can make a gradient gel being more accurate and more stable in quality. When liquid gel enters a collecting trough under continuous driving of a roller in the collecting trough to be injected into a carrier sheet set from a gel output port and a narrow seam, former injected liquid gel can be pushed upwards by latter injected liquid gel, and an accomplished product of gel can be obtained. If the collecting trough is input with two liquid basic materials, the liquid gel continuously output into the carrier sheet set can have a gradient.