A precise mechanistic model is fundamental in simulation, control and optimization of ethylene pyrolysis process. In the Kumar kinetics model proposed by Kumar and Kunzru, there are ten changeable selectivity coefficients and minor-changeable kinetics parameters in the primary reaction equation. They are mainly determined by oil properties, especially the oil composition. This paper proposes a new method of compromising adjustment solution based on target decomposition strategy and Error Correction Chaos Optimization (ECCO) algorithm to mainly acquire rational primary coefficients, and kinetics parameters when necessary. The core idea is to realize atoms balances of the carbon and hydrogen in the primary reaction, as well as minimum yield errors of products based on ECCO algorithm. It exceeds existing methods mentioned by other literatures in its preferable compromise between overall elemental balances and minimal yield errors. It also takes minor tuning of kinetics parameters into consideration. Moreover, this method has been proven effective and applicable to many naphthas with different properties. These data are from a real ethylene plant. The results are helpful in the design of optimal operational conditions and ultimately in controlling of ethylene cracking furnaces which will be discussed briefly. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.