Abstract: Submerged vegetation is a kind of good feedstuff resources with rich protein, mineral substance and vitamin, but ash and sodium sulfate attached to submerged vegetation affect dainty of cattle and sheep. Taking Fennelleaf Pondweed of Lake Wuliangsuhai as a research case in order to get rid of crude ash attached on the surface of submerged vegetation and find out the best technology parameters for crude ash removal rate, crude ash removal orthogonal experiments were carried out for different moisture contents, rotation speeds and sizes of sieve pore with beater pulverizer, nutrient components of smashed hydrophytes were measured, and variance analyses of these data from different indexes were made. The result shows that crude ash removal effect for about 17% moisture, 4000 r/min rotation speed and 8 mm size of sieve pore is the best and crude ash removal rate can reach 70.8% among which sodium sulfate removal rate is 34.7%. Based on variance analysis, the mathematics model with grey system theory was set up to estimate finished product rate of hydrophytes with maximum error of -1.69%, which lays theoretical foundation for technology parameter optimization of pulverizer.