Embodiments of the present invention disclose an in-cell touch screen panel and a display device, at least one gate signal lines is used as a touch scanning line, a touch readout line is disposed between adjacent columns of pixel units in the array substrate, and a touch unit is disposed in a region defined by the touch scanning line and the touch readout line; each touch unit includes a light sensing sub-unit, a touch electrode and a touch signal control sub-unit; the light sensing sub-unit is connected with the touch signal control sub-unit through the touch electrode, and the control signal output from the light sensing sub-unit varies with the variation of external light and coupling capacitance of the touch electrode; the touch signal control sub-unit is connected with the touch scanning line and the touch readout line respectively, the touch signal control sub-unit outputs the touch sensing signal modulated by the control signal through the touch readout line upon the touch scanning line transferring electrical signals. Compared with a single mode capacitive touch screen panel, the in-cell touch screen panel disclosed in embodiments of the present invention can improve the touch sensitivity of the touch screen panel.