Supermassive black hole binary ( SMBHB ) is expected with the hierarchical galaxy formation model .
Currently , physics processes dominating the evolution of a SMBHB are unclear .
An interesting question is whether we could observationally determine the evolution of SMBHB and give constraints on the physical processes .
Jet precession have been observed in many AGNs and generally attributed to disk precession .
In this paper we calculate the time variation of jet precession and conclude that jet precession is accelerated in SMBHB systems but decelerated in others .
The acceleration of jet precession dP _ { pr } / dt is related to jet precession timescale P _ { pr } and SMBHB evolution timescale \tau _ { a } , { dP _ { pr } \over dt } \simeq - \Lambda { P _ { pr } \over \tau _ { a } } .
Our calculations based on the models for jet precession and SMBHB evolution show that dP _ { pr } / dt can be as high as about -1.0 with a typical value -0.2 and can be easily detected .
We discussed the differential jet precession for NGC1275 observed in the literature .
If the observed rapid acceleration of jet precession is true , the jet precession is due to the orbital motion of an unbound SMBHB with mass ratio q \approx 0.76 .
When jets precessed from the ancient bubbles to the currently active jets , the separation of SMBHB decrease from about 1.46 { Kpc } to 0.80 { Kpc } with an averaged decreasing velocity da / dt \simeq - 1.54 \times 10 ^ { 6 } { cm / s } and evolution timescale \tau _ { a } \approx 7.5 \times 10 ^ { 7 } { yr } .
However , if we assume a steady jet precession for many cycles , the observations implies a hard SMBHB with mass ratio q \approx 0.21 and separation a \approx 0.29 { pc } .