  We present the improved constraints on couplings of solar axions and more
generic bosonic dark matter particles using 737.1 kg-days of data from the
CDEX-1B experiment. The CDEX-1B experiment, located at the China Jinping
Underground Laboratory, primarily aims at the direct detection of weakly
interacting massive particles using a p-type point-contact germanium detector.
We adopt the profile likelihood ratio method for analysis of data in the
presence of backgrounds. An energy threshold of 160 eV was achieved, much
better than the 475 eV of CDEX-1A with an exposure of 335.6 kg-days. This
significantly improves the sensitivity for the bosonic dark matter below 0.8
keV among germanium detectors. Limits are also placed on the coupling $g_{Ae} <
2.48 \times 10^{-11}$ from Compton, bremsstrahlung, atomic-recombination and
de-excitation channels and $g^{eff}_{AN} \times g_{Ae} < 4.14 \times 10^{-17}$
from a $^{57}$Fe M1 transition at 90\% confidence level.
