The 110-111 formaldehyde(H2CO)absorption line and H110α radio recom-bination line(H RRL)are observed towards the giant HII region in cloud complex W43.The observations are obtained using the Nanshan 25 m single dish operated by Urumqi Observatory,National Astronomical Observatories of China.A region about30′× 30′ iS observed,which covers the whole HII region in W43.Except for the central 10′ region,all the other seven points are first observed with the H2CO 110-111 absorption.The column density Of the H2CO iS calculated.and the H2CO density contours show some differences with the infrared image.Multiple features appear in the H2CO and H RRL which indicate complex structure.The intensities of the H2CO and the velocities of the H110α seem tO present a linear correlation,which illustrates that the sphere of influence of the central WR/OB cluster may be much more extended than presently known,since the size iS nearly 50 pc.