Abstract: Guiding-deflection technique is one of efficient technical ways toprotect engineering constructions against precision-guided weapons. In thispaper, ductalloy guiding-deflection cones (GDC) are adopted, andsimulated impact tests with 37\,mm semi-armour piercing projectiles arecarried out to test the guiding-deflection performance of the GDC structure.Test results indicate that the structure can make the projectile deflectmore than 10 degrees, and the penetration depth into the target isreduced to less than its 1/3. On the basis of test results, theguiding-deflection mechanism of GDC as well as the test errors areanalyzed, and a conclusion is reached that a space with as small resistanceas possible behind the guiding-deflection structure is one ofprerequisites to achieve large deflection angles. Theguiding-deflection structure can be applied in some importantengineering constructions of national defence and civil-air defence.