In this proposed study, the investigators will evaluate the safety and efficacy of lipoic acid in treatment of Amyotrophic lateral sclerosis (ALS). The study will recruit 150 AD patients, and then these patients will be randomized to lipoic acid group or control group (75 patients per arm) for 6 courses for about 5 months. Clinical assessment will be done at screen/baseline, 3th course and 6th course. The specific aims are to compare lipoic acid versus control on: motor function and disease progression. During the study period, clinical effect index will be recorded, including bulbar function, motor function, respiratory function, and safety index including blood and urine routine, liver and kidney function, coagulation function.

In this proposed study, the investigators will evaluate the safety and efficacy of Lipoic acid in treatment of ALS. The study will recruit 150 ALS patients, then these patients will be randomized to lipoic acid group or control group (75 patients per arm) for 6 courses for about 5 months. Clinical efficacy and safety assessment will be done at screen/baseline, 3th course and 6th course. The specific aims are to compare lipoic acid versus placebo on: (1) Lipoic acid could improve the motor function, delay the disease progression and extend survival time in patients with ALS, measured by the ALSFRS-R Scale, ROADS Scale, upper motor neuron Scale, Muscle strength Scale and Electromyography; (2) Lung function will be collected to prove the hypothesis lipoic acid may help respiratory function. (3) Safety index including blood and urine routine, liver and kidney function, coagulation index will be recorded.

Inclusion Criteria:

1. Age range from 20 to 75 (including 20 and 75 years old), regardless of ethnic group or gender;
2. The subjects should meet the diagnostic criteria for ALS by El Escorial revised criteria: "Definite ALS", "Probable ALS" and "Probable, laboratory-supported ALS".
3. ALS Functional Rating Scale-Revised (ALSFRS-R 12 items) each item score ≥2 points;
4. The onset (the symptoms of limbs weakness, muscle atrophy or bulbar involvement ) of the disease is less than 2 years
5. Baseline breath function: Forced Vital Capacity≥70% .
6. Disease Progression Rate FS=(48- ALSFRS-R at "time of diagnosis")/duration from onset to diagnosis (month), progression rate FS≤1;

Exclusion Criteria:

1. Combined with one of cerebrovascular disease, spinal cord disease, spinal muscular atrophy, juvenile myoatrophy of distal upper extremity, multifocal motor neuropathy, Kennedy disease, epilepsy, etc;
2. Severe renal insufficiency: creatinine clearance rate <30 mL/min (Cockcroft-Gault formula, urea nitrogen and (or) blood creatinine> 1.5 times the upper limit of normal, or other known severe renal insufficiency diseases;
3. Severe liver damage: ALT, AST> 3 times the upper limit of normal, or other known liver diseases such as acute and chronic hepatitis, cirrhosis, etc.;
4. Obvious tachycardia or bradycardia; patients with acute myocardial infarction or interventional therapy in the past 6 months (patients with grade III-IV according to NYHA classification);
5. Combined with malignant tumor, blood, digestion or other serious diseases;
6. Female patients during pregnancy and lactation;
7. Participated in other clinical trials within 30 days before randomization, or are participating in other clinical trials;

outcomes assessors who do all the scales are concealed of group allocation.