A grinding machine for grinding non-horizontal grinding surfaces, comprising: a grinding power source and a grinding pad driven by the grinding power source to perform a grinding stroke on a non-horizontal grinding surface, the grinding pad being made of an elastic material and being configured to take a deformed state for adapting to the non-horizontal grinding surface; and a deformation device disposed between the grinding power source and the grinding pad, the deformation device comprising at least one receiving unit for holding the grinding power source and two offset units disposed between the grinding pad and the receiving unit, wherein the receiving unit defines a reference horizontal line and the two offset units are respectively disposed near two opposite ends of the receiving unit, said deformation device further comprising at least one first deformation member connected between each of the offset units and the receiving unit; wherein, when the grinding pad performs the grinding stroke on the non-horizontal grinding surface to generate the deformed state, the at least one first deformation member is able to be deformed independently to define a first deformation angle formed between anyone of the offset units and the reference horizontal line of the receiving unit, characterized in that said deformation device further comprises at least two second deformation members disposed oppositely and connected between each of the offset units and the grinding pad, wherein, when the grinding pad performs the grinding stroke, the at least two second deformation members are able to be deformed to define a second deformation angle formed between the grinding pad and the reference horizontal line of the receiving unit. a grinding power source and a grinding pad driven by the grinding power source to perform a grinding stroke on a non-horizontal grinding surface, the grinding pad being made of an elastic material and being configured to take a deformed state for adapting to the non-horizontal grinding surface; and a deformation device disposed between the grinding power source and the grinding pad, the deformation device comprising at least one receiving unit for holding the grinding power source and two offset units disposed between the grinding pad and the receiving unit, wherein the receiving unit defines a reference horizontal line and the two offset units are respectively disposed near two opposite ends of the receiving unit, said deformation device further comprising at least one first deformation member connected between each of the offset units and the receiving unit; wherein, when the grinding pad performs the grinding stroke on the non-horizontal grinding surface to generate the deformed state, the at least one first deformation member is able to be deformed independently to define a first deformation angle formed between anyone of the offset units and the reference horizontal line of the receiving unit, characterized in that said deformation device further comprises at least two second deformation members disposed oppositely and connected between each of the offset units and the grinding pad, wherein, when the grinding pad performs the grinding stroke, the at least two second deformation members are able to be deformed to define a second deformation angle formed between the grinding pad and the reference horizontal line of the receiving unit.