By studying the numerical calculation of the stochastic-dynamics equation o
f the laser-DNA interaction, it was found that with the approximation of sm
all signal and adiabatic hypothesis and under suitable conditions, the stoc
hastic chaos will occur in the laser-DNA interactive system. The appearance
of stochastic chaos is related to the intensity of laser. When it is very
weak there is no chaos and this suggests that small intensity of laser does
not make DNA mutate. When laser intensity reaches a certain value, chaos a
ppears and makes DNA mutate. With the increase of laser intensity, the char
acteristic of chaos in the evolution process of system becomes more and mor
e significant. However, laser intensity can not be too strong, otherwise it
will cause very complex chaos that makes a severe problem of uncertainty i
n laser breeding and brings uncontrollable results instead of inducing DNA
to mutate. The influence of the periodical change of environment on laser-D
NA interactive system was discussed, too.