The invention provides a TFT substrate manufacturing method and a TFT substrate. The method employs the SPC (
Solid Phase
Crystallization) technology to prepare an LTPS (Low Temperature Poly-
Silicon) layer, and can reduce costs and form crystalline grains with better uniformity compared with the
excimer laser crystallization technology; meanwhile, a bigrid structure is introduced, thereby enhancing the control of grids to channels, increasing the on state current of a film
transistor, reducing off state current, inhibiting warping effects, reducing a
threshold voltage and a subthreshold gradient, and improving the driving capability of the film
transistor; besides, top grids can cover light, and reduce channel photoinduced electric leakage. The invention provides the TFT substrate, the LTPS layer of which is prepared through the SPC technology, and the TFT is low in production costs; in addition, the TFT substrate is provided with the bigrid structure, allowing the film
transistor to have better electric property and strong driving capability, and not easy to generate channel photoinduced electric leakage.