The bond length is affected by

In a chemical molecule, the bond length should be affected by electro negativity (E.N) hybridization is involved and delocalization (pi electrons movement).

$\mathrm{sp}<{\mathrm{sp}}^2<{\mathrm{sp}}^3$(Bond length increasing order).

$\mathrm{sp}>{\mathrm{sp}}^2>{\mathrm{sp}}^3$(Electro negativity decreasing order)

Note: If ‘s’ character increases then E.N also increased ; therefore bond length get decreased.