  Narrow-line Seyfert 1 galaxies (NLS1s), a subclass of active galactic nuclei
(AGNs) at early stage of accretion process, are also found to host relativistic
jets. However, currently known jetted NLS1s are rare. The majority of NLS1s are
undetected at radio band. The radio detection rate of NLS1s raises with the
LOFAR Two-metre Sky Survey (LoTSS), which gives a good opportunity to find more
jetted NLS1s. The better sensitivity brings another question of whether the
radio emission of NLS1s with low radio luminosity originates from jet activity.
In order to clarify the origin of radio emission for NLS1s, and search for more
jetted NLS1s, we explore the mid-infrared properties of LoTSS detected NLS1s by
comparing them with known jetted AGNs and star forming galaxies (SFGs), which
locate above and on the well studied radio/far-infrared correlation,
respectively. The majority of NLS1s show mid-infrared (MIR) excess compared
with SFGs. Their radio emission shows significant correlation with MIR
emission. In MIR color-color diagram, NLS1s are overlapped with flat spectrum
radio quasars, but well separated from SFGs and optically selected radio
galaxies. The flux ratio between radio and MIR emission of these NLS1s is also
similar with a radio quiet quasar with weak jet. These results imply
substantial contributions from AGN activities for both radio and MIR emission
of NLS1s. A small fraction of NLS1s with relatively higher radio luminosity
locate in similar region with blazars in radio-MIR diagram, which suggests that
the radio emission of these NLS1s is dominated by jet. We obtain a sample of
jetted NLS1 candidates through their radio excess in radio-MIR diagram.
