Using Revised Bloom's Taxonomy (RBT), this study has examined the intellectual demands of the Senior High School Chemistry Curriculum (SHSCC) in China from a socio-historical perspective. Document analysis was adopted as a research method to analyze knowledge types and cognitive processes, the two dimensions of the cognitive learning objectives in the three curriculum documents of the SHSCC officially released in 1996, 2003, and 2018 respectively. The changing tendencies of the two dimensions have been found over the past two decades. As for knowledge types, Factual knowledge has increased, whilst Conceptual knowledge has decreased and Procedural knowledge has dramatically increased, and Meta-cognitive knowledge has appeared recently although in a low ratio. With regard to cognitive processes, the lower levels have been decreased, while the higher levels have been increased. Moreover, explanations have been provided for the association between the orientations of the chemistry curriculum and the extents of intellectual demands embodied in the cognitive learning objectives in these versions of the SHSCC. From these findings, it is concluded that the SHSCC in China has become increasingly demanding during the period under study and the newly emergent SHSCC is more challenging than its predecessors. The implications of this study for curriculum researchers, curriculum developers and chemistry teachers are discussed in the last part of this paper.