In this article, the synthesis and growth mechanism of CaWO4:Eu3+ hierarchical dumbbell-like and double-broccoli-like microstructures via a surfactant-free hydrothermal process are studied. Results show that morphology of the product is time-dependent under proper pH = 7. The formation of double-broccoli-like microstructures experience pathway from nanoparticles to hierarchical configuration. We propose that nuclei aggregated nanorods fused into spindles in seek of less surface energy, and then aligned by reorientation forming the building blocks of hierarchical dumbbell-like and double-broccoli-like morphologies by the “Orientation Attachment (OA) process.” The hierarchical double-broccoli-like microcrystals are grown at the cost of nanoflakes experiencing the “Ostwald Ripening (OR) Process”. Interestingly, the cooperation of “OA process” and “OR Process” is observed in the growth of alkali metal tungstate for the first time. Also, the morphology dependent photoluminescent (PL) properties are also discussed. It may bring us a new insight into the growth of CaWO4 crystals and raise a new way for the fine controlling and designing of other crystals.