The ammonium persulfate is used to oxidize the alkali lignin to prepare oxidized alkali lignin with low molecular weight and more polar functional groups. The prepared high-performance lignin-based grinding aid GCL6-J is evaluated by grinding experiment, the results show that the 45μm screen residue values of the milled cements decrease from 7.8% to 5.3% at the dosage of 0.1% (occupy the total clinker and composite materials by mass), which is equivalent to the 89.3% grinding effect of triethanolamine. The long-term breaking and compression strengths of the milled cement using GCL6-J reach or exceed those of triethanolamine. The combination property evaluation indicates that the GCL6-J belongs to lignin-based high-performance grinding aid. The XPS spectrum analysis shows that the thickness of the adsorption layer of the oxidized alkali lignin is 1.02nm (calculated by the Si), while that of the alkali lignin is 0.41nm. The C1S content of the milled cement using GCL6-J decreases from 38.11% (blank) to 34.07%, while the Ca2p and Si2p contents increase from 8.51% and 4.42% (blank) to 10.29% and 4.98%,respectively, which demonstrates the grinding mechanism of GCL6-J in the milling process: adsorbs on the new-born high energy active sites of the cement surface and masks the charge.