A concealed hinge with a temporary positioning function for an opening angle, wherein the concealed hinge is adapted to be mounted in a door frame and a door, and the concealed hinge comprises: a first base adapted to be mounted in the door frame; a second base adapted to be mounted in the door; a pivotal-connecting assembly connected to the first base and the second base; the first base and the second base being capable of pivoting relative to each other via the pivotal-connecting assembly; the pivotal-connecting assembly having a connecting block located in the second base; wherein when the first base and the second base pivot relative to each other, the connecting block moves relative to the second base; a positioning assembly having a positioning base securely mounted on the second base, adapted to be mounted in the door, and having a connecting passage formed inside the positioning base; and a connecting rod moveably mounted in the connecting passage; characterized in that the positioning assembly has T at least one positioning passage formed inside the positioning base and having an inner end communicating with the connecting passage on a radial direction of the connecting passage; and an outer end opposite to the inner end; a connecting screw end located outside the connecting passage and connected to the connecting block of the pivotal-connecting assembly; wherein when the first base and the second base pivot relative to each other by the pivotal-connecting assembly, the connecting block of the pivotal-connecting assembly moves the connecting rod in the connecting passage; and at least one positioning groove formed on an annular surface of the connecting rod and selectively aligned to the inner end of the at least one positioning passage along with the movement of the connecting rod; at least one positioning unit moveably mounted in the at least one positioning passage; and at least one elastic unit mounted in the at least one positioning passage and pushing the at least one positioning unit toward the inner end to make the at least one positioning unit protrude out of the inner end and abut the annular surface of the connecting rod; wherein when the at least one positioning groove of the connecting rod is aligned to the inner end of the at least one positioning passage, the at least one positioning unit is pushed by the at least one elastic unit and protrudes into the at least one positioning groove, such that the positioning unit stops the connecting rod from further moving and stops the connecting block from moving relative to the second base, and thus the first base and the second base cannot pivot relative to each other. a first base adapted to be mounted in the door frame; a second base adapted to be mounted in the door; a pivotal-connecting assembly connected to the first base and the second base; the first base and the second base being capable of pivoting relative to each other via the pivotal-connecting assembly; the pivotal-connecting assembly having a connecting block located in the second base; wherein when the first base and the second base pivot relative to each other, the connecting block moves relative to the second base; a positioning assembly having a positioning base securely mounted on the second base, adapted to be mounted in the door, and having a connecting passage formed inside the positioning base; and a connecting rod moveably mounted in the connecting passage; characterized in that the positioning assembly has T at least one positioning passage formed inside the positioning base and having an inner end communicating with the connecting passage on a radial direction of the connecting passage; and an outer end opposite to the inner end; a connecting screw end located outside the connecting passage and connected to the connecting block of the pivotal-connecting assembly; wherein when the first base and the second base pivot relative to each other by the pivotal-connecting assembly, the connecting block of the pivotal-connecting assembly moves the connecting rod in the connecting passage; and at least one positioning groove formed on an annular surface of the connecting rod and selectively aligned to the inner end of the at least one positioning passage along with the movement of the connecting rod; at least one positioning unit moveably mounted in the at least one positioning passage; and at least one elastic unit mounted in the at least one positioning passage and pushing the at least one positioning unit toward the inner end to make the at least one positioning unit protrude out of the inner end and abut the annular surface of the connecting rod; wherein when the at least one positioning groove of the connecting rod is aligned to the inner end of the at least one positioning passage, the at least one positioning unit is pushed by the at least one elastic unit and protrudes into the at least one positioning groove, such that the positioning unit stops the connecting rod from further moving and stops the connecting block from moving relative to the second base, and thus the first base and the second base cannot pivot relative to each other.