  We have conducted a line survey towards Orion KL using the Q-band receiver of
Tianma 65 m radio telescope (TMRT), covering 34.8--50 GHz with a velocity
resolution between 0.79 km s$^{-1}$ and 0.55 km s$^{-1}$ respectively. The
observations reach a sensitivity on the level of 1-8 mK, proving that the TMRT
is sensitive for conducting deep line surveys. In total, 597 Gaussian features
are extracted. Among them, 177 radio recombination lines (RRLs) are identified,
including 126, 40 and 11 RRLs of hydrogen, helium and carbon, with a maximum
$\Delta n$ of 16, 7, and 3, respectively. The carbon RRLs are confirmed to
originate from photodissociation regions with a $V_{\rm LSR}\sim$9 km s$^{-1}$.
In addition, 371 molecular transitions of 53 molecular species are identified.
Twenty-one molecular species of this survey were not firmly detected in the Q
band by Rizzo et al. (2017), including species such as H$_2$CS, HCOOH,
C$_2$H$_5$OH, H$_2^{13}$CO, H$_2$CCO, CH$_3$CHO, CH$_2$OCH$_2$, HCN $v_2=1$,
and CH$_3$OCHO $v_t=1$. In particular, the vibrationally excited states of
ethyl cyanide (C$_2$H$_5$CN $v$13/$v$21) are for the first time firmly detected
in the Q band. NH$_3$ (15,15) and (16,16) are identified, and they are so far
the highest transitions of the NH$_3$ inversion lines detected towards Orion
KL. All the identified lines can be reproduced by a radiative transfer model.
