Objective: To assessing the characteristics of of microbial species and the antimicrobial resistance in a Tertiary Hospital with 49 outpatient clinics and emergency department in Northwestern China, of six years. Methods: A retrospective study was conducted using HIS database of a tertiary hospital between the full-year period of 2013 and 2018. Antimicrobial susceptibility tests were conducted by automated systems and/or the Kary-Bauer disc diffusion method. Data were analyzed using the WHONET 5.6 software. The Cochran–Armitage test was used to study the trends over the period. Results: A total of 19,028 specimens were submitted for the laboratory tests of microbiology. Among 49 units, only Emergency Department and Kidney Transplantation Clinic with the number of submission showed a significant increase annually (P<0.001). A total of 3,849 non-repetitive isolates were identified, covering more than 200 species, of which gram-positive cocci accounted for 46.4% and gram-negative bacilli 45.3%. The methicillin-resistant rates of S. aureus and S. epidermidis were 25.1% and 74.6%, respectively. The isolates of 60.9% of E. coli and 33.5% of K. pneumonia contained extended spectrum β lactamases. Moreover, there were no Staphylococci and Enterococci resistant to linezolid, vancomycin and tigecycline. In addition, the percentages of E. coli, K. pneumonia and P. aeruginosa isolates resistant to carbapenems were low (0.0%, 1.1% and 18.7%, respectively). Conclusion: Vancomycin, linezolid and tigecycline are among the most effective treatment for outpatients with gram-positive infection. Carbapenems are among the most effective for gram-negative infection. There is no significant annual increase of common multidrug resistances.