A touch display panel includes a display structure and a touch structure. The display structure includes pixels having a first pitch P1. The touch structure includes a touch layer having slits and dummy clefts. The slits and the dummy clefts have a second pitch P2 and a third pitch P3, respectively. Two adjacent vertices of each slit define a line segment having a length Ly.A first moire ratio (MR1) defined as P ⁢ ⁢ 2 P ⁢ ⁢ 1 satisfies: 20.7%×A1+8.5%×B1−3%≤MR1≤12.7%×A1+16.5%×B1+3%, wherein A1 is an integer from 0 to 3, B1 is an integer from 1 to 3, and 0≤B1−A1≤1. A second moire ratio (MR2) defined as P ⁢ ⁢ 3 P ⁢ ⁢ 1 satisfies: 20.7%×A2+8.5%×B2−3%≤MR2≤12.7%×A2+16.5%×B2+3%, wherein A2 is an integer from 0 to 3, B2 is an integer from 1 to 3, and 0≤B2−A2≤1. An arrangement ratio (LR) defined as Ly P ⁢ ⁢ 1 satisfies: (2C+1)×25%−20%≤LR≤(2C+1)×25%+20%, wherein C is an integer from 0 to 11.