Psoriasis may bring damage to kidney damage. We conducted a seven-year retrospective study focusing on blood examination of renal function of psoriatic patients. Only those first-time hospitalizations with psoriasis were included. We mainly evaluated the renal function indexes on the first day of hospitalization, including Blood Urea Nitrogen (BUN), Serum Creatinine (Scr) and Blood Uric Acid (BUA) of psoriatic patients and 42 non-psoriasis control subjects. We also analysed the correlation between hospital stays and renal function indexes. A total of 123 moderate-to-severe Psoriasis Vulgaris (PV), 55 Erythrodermic Psoriasis (EP) and 33 Generalized Pustular Psoriasis (GPP) were reviewed. The abnormality rate of BUA in EP was significantly higher than that in PV, GPP and Control Group (CG). The abnormality rate of BUN or Scr presented no significant difference between PV, EP and GPP. The absolute value of BUN in PV was significantly higher than that in EP and GPP. The Scr value in PV was obviously higher than that in GPP. The BUA value in EP was clearly higher than that in GPP and CG. There was no significant correlation between hospital stays and the value in BUN, Scr or BUA. Taken together, EP had more significant hyperuricemia and the patients with EP or GPP need to take in protein actively because of their relative low-level of BUN.