As an important water resource of Shandong Province, groundwater plays a great role in the social and economic development. In recent 20 years, the external environmental changes have consequently led to the changes of groundwater resources. The advanced recognition of variation rules and the improvement of evaluation methods could reflect the changes of groundwater resources at some degree. This paper gives a preliminary analysis about the changes of groundwater resources by contrasting the main factors and final conclusions between the first and second groundwater resources assessment. It also provides basis for the reasonable exploitation on utilization of Shandong groundwater resources.