Inclusion Criteria:  18-70 years of age; Clinical diagnosis of PsA according to the CASPAR classification criteria Active PsA at baseline defined as ≥ 3 tender joints and ≥ 3 swollen joints If subjects were taking csDMARDs, the doses of csDMARDs had to be stable for at least 4 weeks and had to remain the same during the trial  The application of bDMARDs and tsDMARDs should meet the following requirements:  Etanercept and its biological analogues: stop at least 4 weeks prior to their baseline visit; Other biological: stop at least 6 months prior to their baseline visit tsDMARDs: stop at least 8 weeks prior to their baseline visit If subjects were taking glucocorticoids, the doses of GC(prednisone < 10mg) had to be stable for at least 4 weeks and had to remain the same during the trial; Non steroidal anti-inflammatory drugs: if applied, the dose was stable one week prior to their baseline visit Negative pregnancy test for child-bearing women at screening and baseline Provide written informed consent  Exclusion Criteria:  Patients with severe heart, liver, kidney and other important organ diseases Abnormal liver function (ALT or AST is 2 times higher than normal) White blood cell count less than 4,000/mm^3 (less than 4 X 10^9/L) Platelet count less than 100,000/mm^3 (less than 100 X 10^9/L) Serum creatinine more than or equal to 1.5 mg/dL (less than or equal to 132.6 μmol/L) Pregnancy or breastfeeding women Contraindications to 99Tc-MDP therapy and/or known hypersensitivity to 99Tc-MDP Participated in other drugs clinical trials within 4 weeks