The spherical flame speed of 1,3-butadiene is studied at 1-18atm in experiments and simulations. The presently measured 1,3-butadiene/air flame speeds are lower than the previous studies. It shows a large uncertainty in the reported measured flame speeds from the linear extrapolation and flow compression correction. At high pressure and fuel lean conditions, Zhou's 1,3-butadiene kinetic model (2018, in press) over-predicts the flame speeds significantly. According to the 1,3-butadiene flame speed sensitivity analysis, C0-C2 small hydrocarbon chemistry and addition reactions of 1,3-butadiene with O/H radicals dominate the reaction kinetics. Especially, the chain branching and termination reactions of 1,3-C4H6 + O = C2H3 + CH2CHO and 1,3-C4H6 + O = CH2O + C3H4-a have large uncertainties for the 1,3-butadiene flame speed prediction. By changing the branching ratio of these two competing 1,3-butadiene + O reactions and replacing the C0-C2 chemistry by HP mech (Zhao, 2017), an updated kinetic model is develop to predict the 1,3-butadiene high pressure flame speeds at both lean and rich conditions. It shows that the present model improves the predictions significantly, especially at the fuel lean condition.