Traditionally, the beam splice assemblies of column-tree connections are designed according to the full-strength designprinciple. Actually, the beam splice is set up at a certain distance from the column face, thus the plastic moment capacity ofthe beam splice does not need to be greater than the plastic moment capacity of the beam. This paper experimentally presentsthe effects of the weakened beam splice on the seismic performance of column-tree steel moment connections. Cyclic tests oftwo column-tree connection specimens with weakened beam splices and one specimen following the full-strength designprinciple were conducted to verify their inelastic behavior and failure modes. The test results showed that the moment resistingcapacity of the column-tree connection specimens with weakened beam splices did not obviously decrease. Also, their energydissipation capacity was better than that of the specimen following the full-strength design principle.