From the perspective of development sociology theory, this paper focuses on “water”, the demand variable that triggers social development. This paper examines Zhang Jian’s pioneering contribution and pivotal role in China’s water conservancy modernization transformation during the accelerated introduction of industrial civilization in the early 20th century. First, based on the change in the power balance between people and water, Zhang Jian dialectically understood the social resource attribute of water, established the awareness of water rights, took the lead in advocating the concept of marine water rights and the practice of protecting rights by law, and restructured the value of water resources through multi-objective comprehensive development, thus realizing the ideological transformation from “natural water” to “resource water”. Second, based on the reconstruction of water’s resource, right attribute, and value, Zhang Jian committed to balancing efficiency objectives with diverse stakeholders and advocated the establishment of basin-based professional water management institutions and a unified national water administration system, laying the organizational and institutional foundations for modernization of water conservancy, and realizing the transformation from acting independently to systematic planning. Third, Zhang Jian broke through the traditional experience, advocated “transmutation in a scientific way”, created a water conservancy education to cultivate “talents that are not measured by money”, scientifically formulated systematic river-basin plans, widely applied modern engineering technology, and took “surveying and mapping as the first” based on the national reality, thus profoundly shifting water management from “experience-based” to “science-driven” methods. Zhang Jian not only promoted the organic integration of traditional Confucian thoughts and industrial values but also realized the paradigm transformation of China’s water conservancy modernization from passive adaptation to active advancement, which has a far-reaching impact and critical insights for innovating China’s contemporary water governance theory and modernizing water management capabilities.