  Space-based gravitational wave (GW) detectors are expected to detect the
stellar-mass binary black holes (SBBHs) inspiralling in the low-frequency band,
which exist in several years before the merger. Accurate GW waveforms in the
inspiral phase are crucial for the detection and analysis of those SBBHs. In
our study, based on post-Newtonian (PN) models, we investigate the differences
in the detection, accuracy requirement, and parameter estimation of SBBHs in
the cases of LISA, Taiji, and their joint detection. We find that low-order PN
models are sufficient for simulating low-mass ($\le 50\ \mathrm{M}_\odot$)
SBBHs population. Moreover, for detectable SBBHs in space-based GW detectors,
over 90% of the GW signals from low-order PN models meet accuracy requirement.
Additionally, different PN models do not exhibit significant differences in
Bayesian inference. Our research provides a comprehensive reference for
balancing computational resources and the desired accuracy of GW waveform
generation. It highlights the suitability of low-order PN models for simulating
SBBHs and emphasizes their potential in the detection and parameter estimation
of SBBHs.
