  We observed the H2CO(110-111) absorption lines and H110{\alpha} radio
recombination lines (RRL) toward 180 NH3 sources using the Nanshan 25-m radio
telescope. In our observation, 138 sources were found to have H2CO lines and 36
have H110{\alpha} RRLs. Among the 138 detected H2CO sources, 38 sources were
first detected. The detection rates of H2CO have a better correlation with
extinction than with background continuum radiation. Line center velocities of
H2CO and NH3 agree well. The line width ratios of H2CO and NH3 are generally
larger than 1 and are similar to that of 13CO. The correlation between column
densities of H2CO and extinction is better than that between NH3 and
extinction. These line width relation and column density relation indicate H2CO
is distributed on a larger scale than that of NH3, being similar to the regions
of 13CO. The abundance ratios between NH3 and H2CO were found to be different
in local clouds and other clouds.
