The invention discloses a telescopic tunneling immediate support device, which effectively solves the problem of unavailable continuous roof contact or poor roof contact capability existing in the prior art during use. The support device comprises hydraulic upright posts, beams and longitudinal beams, and is characterized in that: the bottom of each hydraulic upright post is provided with a base;the beams comprise a front beam, a middle beam, a rear beam, a main support beam and an auxiliary support beam which are arranged in parallel with one another; the longitudinal beams comprise a frontelastic longitudinal beam, a middle elastic longitudinal beam, a rear elastic longitudinal beam, a front rigid longitudinal beam, a middle rigid longitudinal beam, a rear rigid longitudinal beam and a side rigid longitudinal beam which are arranged in parallel with one another and are vertical to the beams; a push hydraulic cylinder is hinged between every two beams respectively; and the elastic longitudinal beams and the rigid longitudinal beams are fixed on corresponding beams respectively, inserted in limiting guide sleeves of corresponding beams and driven to move along the limiting guidesleeve in a reciprocating way by the beams. The support device has the advantages of reasonable structural distribution, convenience for adjusting continuous roof contact, stable supporting and capabilities of improving the operating environment of workers, better meeting the requirement on matching job of an underground laneway support and a roadheader and remarkably improving the support quality and tunneling operation efficiency of a laneway top plate.