A new and distinct cultivar of Thuja tree named ‘；RLH-CS’；, characterized by its relatively compact, upright and narrowly pyramidal plant form； moderately vigorous growth habit and moderate to low growth rate； freely branching habit； dense and bushy form from base to top of the tree； lateral branches that are fine-textured and flexible and resist cracking and splitting； dark green-colored leaves that are soft and fine-textured and tolerate high humidity and high temperatures conditions； and good garden performance.
