Accreting pulsars are highly magnetized neutron stars in binary systems. They accrete material from the donor star and release the gravitational energy into X-rays. They generally exhibit complex timing and spectral variations at different accretion regimes depending on the accretion rate and the magnetic field. In the past few years, Insight-HXMT and NICER have provided broadband and high-cadence observations with complete coverage of several luminous outbursts of accreting X-ray pulsars. In this talk, we will introduce the detailed evolution of pulse profiles, spectral shapes and cyclotron resonant scattering features over a large luminosity range, and discuss the related theoretical models.