This article summarized Professor TU Jinwen's experience in treatment of intracranial atherosclerotic stenosis （ICAS） with principles of supplementing deficiency， resolving toxins and unblocking Collaterals. He believes that toxin damaging brain collaterals is the core pathogenesis of ICAS， and thereafter proposed supplementing deficiency， resolving toxins， and unblocking collaterals be the basic treatment method. The emptiness of brain collaterals is the source of the disease. For cases where there is spleen kidney depletion and insufficiency of original

qi

， the modified

Sijunzi Decoction and Liuwei Dihuang Pills

（四君子汤合六味地黄丸） could be used to fortify the spleen and tonify the kidneys to enrich the collaterals. The accumulation of turbidity stasis toxin in

brain collaterals is essential components of the pathogenesis. For cases where turbidity and stasis combine together， inducing toxins and obstructing the colla-terals， the modified

Taohong Siwu Decoction and Erchen Decoction

（桃红四物汤合二陈汤） could be used to eliminate toxins and dispel knots to unblock the collaterals.

Yin

toxins obstructing the latent collaterals represent the gradual progression of pathogenic factors. For cases where turbid stasis transform into cold and

yin

toxins hide in the collaterals， the modified

Buyang Huanwu Decoction and Ditan Decoction

（补阳还五汤合涤痰汤） could be used to remove the toxin， warm and activate the collaterals. Heat toxins damaging the collaterals signify aggravated changes in disease. For cases where turbid stasis transforms into heat and toxins injure the brain collaterals， the modified

Dachaihu Decoction and Huanglian Jiedu Decoction

（大柴胡汤合黄连解毒汤） could be used to cool blood and dredge the fu viscera to clear collaterals.