The present disclosure provides a touch substrate and a touch display device. The touch substrate includes a base substrate, and a first electrode layer and a second electrode layer laminated one on another on the base substrate. The first electrode layer includes first channel patterns and first dummy electrode patterns, the second electrode layer includes second channel patterns and second dummy electrode patterns, the first channel pattern and the second channel pattern are insulated from each other and arranged in such a manner as to cross each other, and the second channel pattern is insulated from the second dummy electrode pattern. Each first dummy electrode pattern includes a first dummy electrode sub-pattern, each second dummy electrode pattern includes a second dummy electrode sub-pattern, and the first dummy electrode sub-pattern is electrically coupled to the first channel pattern and the second dummy electrode sub-pattern.