A touch sensing method and a portable electronic apparatus are disclosed in this invention. The portable electronic apparatus includes a display module, a touch module and a processing unit. The display module is used for displaying a user interface. The user interface includes a plurality of interface layers. Each of the interface layers has a layer depth index respectively. The touch module is used for sensing a touch input. The processing unit is used for mapping the touch input to one of the interface layers according to the touch input and the layer depth indices of the interface layers, so as to select or execute an application function on the one of the interface layers.