A touch electrode layer and a touch display device are provided. By setting first and second electrodes of a touch electrode unit to a trunk and a branch structure, respectively. First electrode branches are electrically connected to first electrode trunks. Second electrode branches are electrically connected to second electrode trunks. The first electrode branches and the second electrode branches form “a homocentric squares pattern” of a limit coupling shape, which can increase rate of change of a basic mutual capacitance value when a finger touches it. In addition, third electrodes having “a homocentric squares pattern” are disposed between the first branch electrodes having a homocentric squares pattern and the second branch electrodes having a homocentric squares pattern and are not connected to the first branch electrodes and the second branch electrodes. This effectively reduces a basic mutual capacitance value Cm and can effectively reduce parasitic capacitance to ground.