Global cropland is expanding rapidly to meet rising food demands, making it essential to enhance crop yield and water productivity (WP) simultaneously, especially in arid regions. In this study, we quantified the synergistic changes of these variables to identify sustainable agriculture pathways based on the spatial-temporal changes of planting area, APSIM-simulated production variables (yield, water consumption (ET), and WP) of wheat and maize in arid Northwest China. Results indicated that planting area, yield, and WP of two crops increased at regional and sub-regional scales from 2000 to 2019, with the exception of declining wheat area in the Hexi Corridor (HX). ET for both crops exhibited decreasing trends. Yield of both crops showed a positive correlation with soil organic matter. The correlations between ET and soil-climate factors were generally consistent for both wheat and maize, except for field capacity. Maize WP was positively correlated with bulk density and negatively with soil total nitrogen. Overall, 55.46% of wheat-growing areas and 78.23% of maize-growing areas exhibited synchronous improvements in planting area, yield, and WP, representing an ideal pathway, while 44.54% of wheat and 21.77% of maize planting areas exhibited asynchronous changes primarily characterized by reduced planting area alongside increased yield and WP. These findings confirmed current positive trends in crop expansion and provided an evaluation framework for promoting coordinated development of area-yield-WP in arid regions.