  We present a narrow $\rm H\alpha$-band imaging survey of 357 low surface
brightness galaxies (LSBGs) that are selected from the spring sky region of the
40% Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) HI Survey. All the
$\rm H\alpha$ images are obtained from the 2.16 m telescope, operated by
Xinglong Observatory of the National Astronomical Observatories, Chinese
Academy of Sciences. We provide the $\rm H\alpha$ fluxes and derive the global
star formation rates (SFRs) of LSBGs after the Galactic extinction, internal
extinction, and [NII] contamination correction. Comparing to normal
star-forming galaxies, LSBGs have a similar distribution in the HI surface
density ($\rm \Sigma_{HI}$), but their SFRs and star formation surface density
($\rm \Sigma_{SFR}$) are much lower. Our results show that the gas-rich LSBGs
selected from the ALFALFA survey obviously deviate from the Kennicutt-Schmidt
law, in the relation between the star formation surface density ($\rm
\Sigma_{SFR}$) and the gas surface density ($\rm \Sigma_{gas}$). However, they
follow the extended Schmidt law well when taking the stellar mass of the galaxy
into consideration.
