An LED illuminating device includes a first LED illuminating module, a second LED illuminating module, and a connecting module. The first LED illuminating module includes a first substrate and a first group of LEDs mounted on the first substrate. The second LED illuminating module includes a second substrate carrying a second group of LEDs, a wedge shaped light guide, and a reflector. The second substrate and the reflector defines a fan shaped space therebetween to receive the wedge shaped light guide, and the projections of the first substrate and the second substrate are spaced to each other. The LED illuminating device has a large light divergence angle and good heat dissipation ability.