Proteinaceous wastewater contains various proteins, which can be valorized to biobased volatile fatty acids (VFAs), important substrates for the synthesis of biodegradable plastics, biodiesel, bioelectricity, etc., but the influence of protein type on VFAs has never been documented. It was found that among the five proteinaceous wastewater proteins investigated, ovalbumin and casein produced the most and the least VFAs, respectively. The mechanism investigation shows that proteins with higher VFAs production had higher functional microorganism abundance and key enzyme activity in the reaction system due to their more enzyme cleavage sites and looser secondary structure, which made it easier for more hydrolase to bind, causing more protein hydrolysis. Also, metaproteomics and amino acid composition analyses revealed that the hydrolysates of proteins with higher VFAs had more isoleucine and proline, which were needed for the synthesis of recognizing and binding proteins (oligopeptide permease subunit A (OppA) and dipeptide permease (Dpp)) of acidogens and beneficial for transporters (Dpp subunit F/Opp subunit F), more hydrolysates (amino acids) were therefore transported into the cell. Further investigation indicates that more electron acceptor and electron donor paired amino acids were in the hydrolysates, facilitating the Stickland reaction and promoting intracellular amino acids bio-transformation to VFAs.