High-sensitivity observations of PSR J1919+1745 were conducted using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) at a central frequency of 1250 MHz, enabling a detailed investigation of its single-pulse behaviour. Our research indicates that this pulsar is a normal pulsar, exhibiting null behaviour, subpulse drifting, and occasional bright pulses. Moreover, we observed that the null events tend to be of short duration, with an estimated overall null fraction of approximately 29.5 ± 1.1%. Through Sliding Fluctuation Spectrum analysis, the modulation period of subpulse drifting is determined to be P3 =(6.1 ± 0.7)P1 (where P1denotes the pulsar rotation period), and a non-drifting behaviour is also observed besides this. Analysis using the Harmonic-Resolved Fourier Spectrum indicates that a combination of amplitude modulation and phase modulation causes the subpulse drifting behaviour of this pulsar. Furthermore, the value P2, derived from phase modulation, is approximately 360°/21 = 17.1°. polarisation analysis shows a moderate degree of linear polarization (37.22 ± 0.59%), an S-shaped swing in the polarisation position angle, and an approximate 90° orthogonal polarisation jump. The radiation characteristics of PSR J1919+1745 will expand the sample of pulsars with pulse null and subpulse drifting, thus contributing to future systematic studies on the physical origins of pulse null and subpulse drifting phenomena.