This article presents the proposal, design, and implementation of 3-D pattern modulation surfaces (PMSs) using short-circuited slotline structure. Firstly, the reflection coefficient of short-circuited slotline with a certain length is studied by using the equivalent transmission line model. Since the magnitude of its reflection coefficient nearly equals 1, the TE-polarized incident plane wave can be almost fully reflected at the input terminal of each short-circuited slotline. Most importantly, the phase of its reflection coefficient can be freely changed and adjusted by only varying the length of short-circuited slotline. Then, the short-circuit slotline structure is utilized as the key element of the proposed PMS. In this way, the functionality of pattern modulation is obtained by unequally selecting the lengths of a row of short-circuited slotlines. Finally, three prototypes with modulated angles of 15°, 30°, and 45° are fabricated and tested to validate our design concept. Measured results agree well with the calculations, showing that the predicted reflection angles are realized by using short-circuited slotlines. Therefore, the proposed 3-D PMS is evidently verified to be a promising candidate for future wireless networks to achieve pattern modulation in a smart radio environment.