Profit reached 26.9 billion yuan ($4.28 billion) for the quarter ended December, down 10 percent from 29.8 billion yuan a year ago. This was, however, better than an average estimate of 25.51 billion yuan from 18 analysts polled by Thomson Reuters.
For 2017, net profit rose about 5 percent to 172.41 billion yuan from 164.578 billion yuan a year ago.
BoC's non-performing loan ratio was 1.45 percent as at end-December, from 1.41 percent at end-September.
Its operating expenses fell 0.69 percent from a year ago to 173.86 billion yuan in 2017, while net interest income rose 10.57 percent to 338.39 billion yuan over the period.
BoC's net interest margins (NIM) - the difference between interest paid and earned by banks - was reported at 1.84 percent for 2017, versus 1.83 percent for the year ago.