The integration of engineering into existing school science curricula is arguably an effort to move beyond a mono-disciplinary goal of learning to one that teaches real-world applications and problem-solving in science. This study adopted dual theoretical lenses to scrutinize and compare the distribution of engineering elements in past and present Grades 1-9 science standards from mainland China, and the types of epistemic access afforded from these engineering-related standards. We found that engineering elements based on Moore et al. ("Journal of Pre-College Engineering Education Research" 4: 1-13, "Journal of Research in Science Teaching" 52: 296-318) in the present standards were more evenly distributed across grade levels (between 21 and 25 elements) compared to the past version that progressively increased learning about engineering up the grade levels from 10 to 40 elements. In contrast to the latter that conformed to a "step-by-step strengthening and deepening" pattern in engineering education in every element across grades/time, the present engineering-related standards have instead emphasized different elements at different grade levels. Moreover, ETool (20.2% in present/38.3% in past), SEM (14.9%/9.9%), and CEE (11.7%/14.8%) were the three most emphasized elements in the present and past standards, but POD, Ethink, ISI, Teamwork and Comm-Engr, and Ethics elements were least frequent. We also adopted Specialization codes from Legitimation Code Theory to examine the opportunities for epistemic access among these past and present engineering-related standards. It was found that the present standards are far more demanding for learners compared to the past due to greater frequency of elite codes (49.4%), which may limit finding success, meaning, and achievement in these topics. Our findings not only suggest some changes for better integration of engineering into the science curriculum in mainland China, but also have implications for the improvement of teacher professional development programs and the development of science curriculum resources/programs for engineering education in this region and elsewhere.