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Pulsar's position, proper motion and parallax are important parameters intiming equations. It is a really challenging work to fit astrometric parametersaccurately through pulsar timing, especially for pulsars that show irregulartiming properties. As the fast development of related techniques, it ispossible to measure astrometric parameters of more and more pulsars in amodel$\textrm{-}$independent manner with the Very Long Baseline Interferometry(VLBI). In this work, we select 16 normal pulsars, whose parallax and propermotion have not been successfully fitted with timing observations or showobvious differences with corresponding latest VLBI solutions, and do furtherstudies on their timing properties. After updating astrometric parameters inpulsar ephemerides with the latest VLBI measurements, we derive the latestrotation solutions of these pulsars with observation data at S andC$\textrm{-}$band obtained from the Shanghai Tian Ma Radio Telescope (TMRT).Compared with spin frequency $\nu$ inferred from previous rotation solutions,the newly$\textrm{-}$fitted $\nu$ show differences larger than 10$^{-9}$ Hz formost pulsars. The contribution of the Shklovsky effect to period derivative$\dot{P}$ can be properly removed taking advantages of accurate proper motionand distance of target pulsars measured by VLBI astrometry. This further leadsto a precise estimate of intrinsic characteristic age $\tau_{\rm c}$.Differences between the newly$\textrm{-}$measured $\tau_{\rm c}$ andcorresponding previous results are as large as 2% for some pulsars. VLBIastrometric parameter solutions also lead to better measurements of timingirregularities. For PSR B0154$+$61, the glitch epoch (MJD 58279.5) measuredwith previous ephemeris is about 13 d later than the result (MJD 58266.4)obtained with VLBI astrometric parameter solutions.

New timing measurement results of 16 pulsars