  Based on Monte Carlo techniques, we analyze the initial state radiation (ISR)
effects in prompt $\jpsi$ inclusive production at B factories. ISR enhances
cross section $\sigma(e^-e^+\to\jpsi+gg+X)$ by about $15-25\%$, which is almost
the same size as the QCD and relativistic correction. Moreover, ISR slightly
changes $\sigma(e^-e^+\to\jpsi+c\bar{c}+X)$. The $\jpsi$ momentum spectrum in
$e^-e^+\to\jpsi+gg+X$ and in $e^-e^+\to\jpsi+c\bar{c}+X$ is softer after the
photon showering from the initial $e^{\pm}$ beam radiation. After combining the
QCD,relativistic, and ISR corrections,a more precise theoretical result is
obtained. The new result provides a more stringent constraint of the
color-octet contribution to $\sigma(e^-e^+\to\jpsi+X_{\rm{non-}c\bar{c}})$.
