  We report on a recent spectral line survey of the planetary nebula (PN) NGC
7027 using the Arizona Radio Observatory (ARO) 12m telescope and the Heinrich
Hertz Submillimeter Telescope (SMT) at millimeter wavelengths. The spectra
covering the frequency ranges 71--111GHz, 157--161GHz, and 218--267GHz were
obtained with a typical sensitivity of rms<8mK. A total of 67 spectral lines
are detected, 21 of which are identified with 8 molecular species, 32 with
recombination lines from hydrogen and helium, and 14 remains unidentified. As
the widths of emission lines from CO, other neutral molecules, molecular ions,
as well as recombination of H+ and He+ are found to be different with each
other, the line strengths and profiles are used to investigate the physical
conditions and chemical processes of the neutral envelope of NGC 7027. The
column densities and fractional abundances relative to H2 of the observed
molecular species are calculated and compared with predictions from chemical
models. We found evidence for overabundance of N2H+ and underabundance of CS
and HNC in NGC 7027, suggesting that X-ray emission and shock wave may play an
important role in the chemistry of the hot molecular envelope of the young PN.
