摘要: The decay widths of four-body double-pion decays $\ds\to pn \pi^0\pi^0$, $\ds\to pn \pi^+\pi^-$, and iso-scalar parts of $\ds\to pp \pi^0\pi^-$ and $\ds\to nn \pi^+\pi^0$ are explicitly calculated with the help of the d∗ wave function obtained in a chiral SU(3) quark model calculation. The effect of the dynamical structure on $\ds$'s width is analyzed both in the single ΔΔ channel and coupled ΔΔ and CC channel approximations. It is found that in the coupled-channel approximation, the obtained partial decay widths of $\ds\to pn \pi^0\pi^0$, $\ds\to pn \pi^+\pi^-$, and those of d∗ to the iso-scalar parts of ppπ0π− and nnπ+π0 are about 7.4MeV, 16.4MeV, 3.5MeV and 3.5MeV, respectively As a consequence, the total width is about 64.5MeV. These widths are consistent with those estimated by using the corresponding cross section data in our previous investigation and also the observed data. But in the single ΔΔ channel approximation, the widths are still almost 2-times larger than the measured values. Apparently, the explicitly calculated width together with the evaluated mass of d∗ in the coupled ΔΔ and CC channel approximation can well explain the observed data, which again supports our assertion that the $\ds$resonance is a six-quark dominated exotic state.